Need an answer????

Okay so I asked before buuut I got one irrelevent answer. I am 37 weeks pregnant and on my HANDS and FOREARMS I keep getting this feeling like bugs crawling on me. Is this a pregnancy thing or something else? And also--Is it possible to pull a muscle in your rectum? Ever since yesterday I had a BM and afterwards by about an hour I got this pain in my and it has never gone away. It hurts really bad when I sit on the toilet or sit straight up. Anybody else feel like this??