Help! Need opinions?!

Okay everyone, I'm sorry if this turns out really long but I will try to explain everything as shortly as possible.

To start out, in 2013 I was involved in an accident, the driver rolled the vehicle and long story short I ended up in the er for six hours in a neck brace and lots of tests done due to severe back, neck, head and side pain and being confused, did not remember my date of birth at first etc. I went through quite a few scans and a urinary test. Tests came back and I was told that I had a little bit of blood internally in my abdomen and that if pain continued to come back to the hospital.

I never went back, after that day I sometimes have severe pain on my left side(if I'm looking down) it starts at the middle of my hip goes down into the left side of my pelvic bone and up along side my belly button on the left side. Sometimes my left leg will go numb. It seems that whatever it is, it is affected by my activity (if I'm being very active it starts) and my menstrual cycle.

But, I started being sexually active in Oct of 2015, and I sometimes experience pain during sex in that area, or I've had very severe pain afterwards.

So I guess my question is, has anyone else ever experienced this? If so, what was it?

Or do you have an idea of what it could be?.

Opinions are very appreciated!!!