Actually, you could be taking percocet or codeine. I was on a huge dosage of percocet when I was pregnant with my second for my entire second trimester. I was having a muscle spasm (sounds minor but it's NOT, it's basically a charlie horse that involves all of the back muscles and lasts for weeks to months with NO relief, the muscle literally seizes up and doesn't let go) in my back. This was not surprising since I get them all the time and have had three back surgeries related to herniated discs and damaged nerves. My muscle spasms are intense. I was crawling (very slowly) around my house and was on crutches (which was excruciating since I didn't tolerate being upright very well) for when I needed to leave the house for physical therapy or dr. appts. My OBGYN prescribed percocet to combat the pain and allow me to sleep. I was in tears without it. It really helped. Of course in a situation like this you have to weigh the risks v. the benefits and my doctor thought the risks were worth it for the relief I could get from it. I needed sleep if I was going to come to delivery healthy enough to see it through. Fortunately, with physical therapy I was able to finally get the muscle spasm to let go of me at the end of that trimester, but MAN was I miserable until it did. 3 months of debilitating, immobilizing, constant pain that almost nothing will help except heavy narcotics...(and even then I still felt it, I just didn't care) not even major muscle relaxers could do more than make a dent in the problem. Not my ideal pregnancy for sure!
However, my son was born a happy, healthy and bouncing 8lbs 8oz exaclty on my due date! He's very bright (really too smart for his own good) and he's a little smart-alecky stinker to boot. I wouldn't have him any other way though. I adore spunk!
Anyways, talk to your doctor about more serious pain relief. Don't hold back. Describe your pain in detail and the effects it's having on you (i.e. not sleeping well or at all, not able to perform daily tasks etc..)