Hi tiny_rooster_girl! Welcome to the forums. I am so sorry you are having such a terrible time with pain. You will find many empathetic and compassionate friends here.
My first thought regarding your IBS C has to do with meds you are currently taking. Speaking for myself, as one who has struggled with C for 30 years, I couldn't take even ONE oxy or hydro without ending up with a colon impaction. These drugs are notoriously constipating. You probably already know that. For those of us who lean toward C, trying to control pain without the aid of drugs like these is a challenge. Are you taking a stool softener?
The degree of pain that I experience daily is always the direct result of the quality of BM's. If I am plugged up at all, I will have discomfort all day long, until I have sufficiently emptied my guts. For me, even gas and trapped gas is the result of waste that is not moving itself out efficiently. The goal is to keep things moving regularly. I manage this by taking herbal supplements daily, drinking TONS of water, avoiding foods that I know will bind me up, and eating foods that I know will help me go. In addition, some kind of activity is helpful in getting things going, even if it's nothing more than cleaning the house or walking to the corner store. When I'm in a particularly bad way with pain, I will use a heating pad on the belly and do some gut massage in an attempt to "stir things up and out". When it comes to medications, the first question I ask the doc is how will it effect my gut. I was recently told I am borderline anemic but I know that iron supplements will cause extreme C. Instead, I have increased my intake of iron rich foods, in conjunction with vitamin C for absorption. Hopefully, I can correct this situation without taking a pill that will cause more problems than the original diagnosis.
Amitiza has been discussed at great length on this forum. Many people have had adverse side effects from this drug. If you check out some of the older threads I am sure you will find lots of info on how people have responded to this treatment.
After 35 years of dealing with IBS, and after taking every drug available to "treat" the symptoms, I have concluded that there is nothing in pill form that is going to work for me. That is only my experience, of course. Many folks found relief with Zelnorm (not on the market any longer) but for me, it had terrible side effects. I've taken the anti-spasmodics, anti-depressants, and anti-anxiety drugs as well. Nothing works for my condition. I have had to turn toward more "alternative" treatments (such as the herbal supplements) and dietary approaches to improve my condition. Even these methods don't work ALL the time. But sometimes the most effective approach is to eliminate the things we know will have a negative effect. It's as good a place to start as any!
Hope this helps!