Pain in the Belly

About a week ago I started having a lot of pain in my lower stomach and It still has not gone away. I went to the Dr Monday to get checked out. The Dr. suspected preterm labor, but thankfully the test came back negative. She has given me pain pills that seem to take the edge off but knock me out at the same time. The pain is now in my back and making me more and more uncomfortable. We are thinking that because the baby is sitting so low that my muscles are stretching. Well whatever it is, it is a horrible feeling. I am getting to the point that picking up Parker is very hard but I do it rather than listening to him scream and yell. I am 26 weeks today, so only 14 weeks (3 1/2 mo) to go. I'm sure it will be here before we know it but it will seem like forever if this pain continues.