Why does my pain change so much?

I found this great picture online and I thought some of my fellow medical background readers as well as pelvic pain suffers might like to see where exactly my pain is. 

One thing I will never be able to figure out is why my pain seems to change so often.  When my sitting pain first began in March my pain was mostly burning pain in my sacrum (the large triangular bone at the bottom on the spine, colored in blue on this picture) that increased when I sat and sometimes shot down into my pelvis.  My PT's and  doctors said I had sacroiliac (SI) joint dysfunction. The SI joint is marked in red. This joint normally doesn't move much, but during pregnancy the ligaments become lax and there can be movement in this joint causing some low back pain. Sometimes I would have pain as high as the SI joint, but most of the time is was lower more in the pink area, which is the sacrotuberous (ST) ligament which connects the sacrum to the "sit bones" (ischial tuberosity).  In October I started having a lot of pain around the "sit bones" (ishcial tuberosity), pictured in purple. After having physical therapy twice a week for 6+ weeks my sit bone pain is a little better, but just this past week or so I've started having a lot of sacral pain again (around where the ST ligament connects to the sacrum). When I have PT my obturator internus muscle is almost always tight as is my piraformis muscle.  Most of my pain is localized to the left side, although I do get pain in the obturator muscles and sit bone area on the right sometimes. 

I think the reason my sacral pain has flared again is because my PT has found that I have a sacral torsion, basically my sacrum is kind of tilted up on the left side.  So she has been manipulating the left side of my sacrum which I think has gotten my ST ligament angry which is causing my piraformis muscle to tighten.  When my sacral area is flared it hurts all the time whether I sit or stand and sometimes even when I lay down.  When my sit bone area is flared it hurts mostly when I sit.

So what is the source of my pain?  Good question.  Well, it is my understanding that nerves are what send pain signals to the brain, not muscles or joints. Now muscles can be injured thus causing the nerve in that area to send signal to the brain that the muscle hurts and joints can get inflammed causing the nerve to that area to alarm the brain that the joint hurts.  So is the source of my pain a muscle/ligament injury? Joint inflammation? or nerve inflammation or even entrapment?  That is what I wish I could figure out. 

I have two theories:

1.) Strangly enough the first PT I went to when I started having sitting pain thought I had right SI joint dysfunction and she manipulated my SI joint several times using an aggressive type of manipulation. At the time I had only occasional lower back pain and no sacral pain.  I think it's possible that PT over corrected my SI joint and hyper extended me causing me to strain some of the ligaments surrounding the SI joint including the left ST ligament.  I was 6 months postpartum and still breastfeeding at the time so my ligaments were still lax from the pregnancy hormone "relaxin".  This strain caused the muscles in my pelvis to tighten and spasm which then irritated and tightened around my pudendal nerve causing my pain with sitting. I have many biomechanical problems (such as the sacral torsion) and due to this and my abdominal weakness from having a baby, my core muscles cannot keep my SI joint/sacrum in alignment so there is constant strain on my sacral area ligaments causing the muscles to tighten and irritate the nerve. A viscous cycle. It's possible that physical therapy actually entrapped the pudendal nerve between the ST and sacrospinous ligament (colored in green) or in another area called Alcock's canal (which is located in the oburtator internus area).  If I have an entrapment the only hope to get better is surgery, and the success rates aren't great.

2.)  The vulvodynia I experienced during pregnancy was unprovoked. It hurt pretty much all the time and burned a lot.  From what I have read many people call this type of vulvodynia pudendal neuralgia, an irritation of the pudendal nerve.  While my vulvodynia greatly improved postpartum, I still had a lot of pain with intercourse (burning afterward) and pain around my vaginal tear site.  Once my periods returned I noticed around ovulation time I had a lot of irritation to wearing certain pants, especially jeans. This pain was similar to what I had in pregnancy just to a much lesser degree. I then went to pelvic floor PT due to pain with intercourse and maybe the PT further irritated an already angry pudendal nerve which brought my pain to a new level (causing me pain when I sat).  It's also possible that the return of my menstrual cycle brought my pain to a new level since my vulvodynia began with pregnancy which was a huge hormonal change.  The sacral pain could be from my SI joint dysfunction and an SI injection of steriods might help it (this will probably be something I pursue if the pudendal block doesn't help me or diagnose me).  In this case I don't think I could have a true entrapment, but rather just the neuralgia. Maybe with hormonal regulation (although I am scared of birth control as hormonal changes seem to aggrevate my pain), the right medications, and PT my pain would slowly (and I mean slowly) decrease.

Or is it a combination of these things in a series of unfortunate events (better known as God's providence :))?  I'll probably never know.  Well, for those that actually read this, there's your anatomy lesson of the day.  I have learned more about anatomy this past year than I did all through nursing school!