34 w &' 6 days ....

Im ending my 34th week on Sunday , baby is head down &' lately I've been feeling really sore down there , like I try to open my legs cris cross &' can't because it hurts so much.. also when I try to have sex I can't because it's just so sore . can anyone tell me why this is happening ? Have any of you other mommas to be or mommas expierenced this ??