What can this be????

AH
I am only 29 weeks & 4 days
& since week 28 I've been having some pelvic pain, especially when I sit or try to roll over in bed. 
I feel pressure and some pain/discomfort. 
I was going to wait till my next appointment appointment to ask the doctor but it isn't till the 8th of July. 
I know y'all aren't doctors, but I'm just wondering if anyone has felt this before. It's my 1st pregnancy so I'm not sure what's normal & what isn't. 
What can this be?? Should I call the doctor?