Echo pretty much everything Wisteria has said. My dh probably has fibro (has never really had a firm diagnosis, because - to be quite honest - clinicians do not care about conditions they cannot treat). The best combo we ever had was tramadol and amitriptyline I think, and a hospital pharmacist took him off it as the combination (at the relevant dosages) can cause psychosis. Wisteria, you might want to double-check on that?
If at all possible, I would avoid moving to a heavier dose of painkillers. My dh is at the end of this particular road, having been on liquid morphine for well over a year and now rotating methadone and dihydrocodeine. You don't want to go there. It doesn't help, it's probably made things worse, and now we don't know what the hell to do, as any withdrawal makes the pain intolerable for dh.
I'm afraid that I'm bang alongside Wisteria in that the drug that helps best is cannabis. I don't really care if anyone wants to shoot me down and tell me that it's harmful. It's not more harmful than morphine, my friends. Drug trials are starting with a cannabis-like agent, but targeted at MS sufferers at present.
A referral to the pain clinic could be good, TENS is an excellent suggestion, have you tried acupuncture? this is a good book which I haven't read as much as I should have, but one of its major recommendations is for heat therapy, mainly hot water in the shower. Have you tried that at all?
Incidentally, I'm convinced dh doesn't really have fibro because he has no good days, no flare ups, it's just bad 24*7. I'd welcome views from diagnosed sufferers as to whether that's consistent with their symptoms.