Braxton hicks at 6 months?

I'm laying in bed and got a painful tightening feeling in my lower abdomen around 7:03. I got another one around 7:011. And another at 7:18.  I'm not sure what it could be because I've changed positions and still had the pain. I know the difference between my baby moving around and the pain. He has always been pretty low and I've stressed to my doctor about it feeling like hes gonna fall out or something because of all the pressure I was having down there. Any ideas? Or should I just call my doctor?