I'm so there with you, girl...it's totally frustrating. I hope your doctor doesn't just shoo you off without a good talk about dealing with this. The last time I ended up in the ER with severe pain my PCP gave me a script for Vicodin and I'm grateful to be able to rely on that the next time everything goes to hell (although sometimes it seems like only the injections do anything!). As far as the daily, run-of-the-mill, annoying pain...are you taking anti-spasmodics? Forgive me if you've told us a million times.
Any time you have severe, incapacitating, huddled-on-the-floor-gasping-for-air pain that lasts longer than a couple of hours, it's likely worth an ER visit. It's a tough call, though, I know. But when I was seven, I went three days with ungodly pain/fever/vomiting before my parents took me to the pediatrician (my dad, a doctor, thought it was indigestion). Turned out my appendix had burst! My parents still feel guilty about that.
I am going to start doing it this way after my last ER visit: if I start getting that kind of pain, and I know it's going to get bad, I'll get myself home, down a dicyclomine and a Vicodin, and wait an hour and a half for them to kick in. If I am still in excrutiating pain after that long, after those meds, I'll get someone to take me to the hospital and let them decide what to do with me!
Hang in there, softy. Vent all you need to!