SEVERE constipation from narcotic/opioid (opiate) use?

I've been taking different narcotics and opioids for a few years now to manage pain and have had constipation pretty regularly. However it seems to have gotten a lot worse the past few months. I would not be posting on here if I've already tried everything that has been suggested-- I drink lots of water, eat my fiber, take 2 stool softeners DAILY for several months, eat my fruit, and have tried several OTC methods (miralax used to work without too many side effects but no result anymore, nothing from the laxatives, suppositories and the little saline enemas that are supposed to just stimulate don't work either. Magnesium citrate has worked before but I took it a few weeks ago with no result (and it's pretty harsh stuff, the problem is now I can't drink enough of it without vomiting it right back up even mixing the lemon flavored with lemonade and the g with g juice :/). I'm not talking mild constipation like a few days either-- over a month ago I had an abdominal/pelvic CT because I was having horrible kidney/flank pain and it showed my intestines were pretty packed with stool. I have gone maybe 3-4 times since then, today being the first time in 3 WEEKS! My abdomen is visibly larger and distended and painful and my back pain is getting worse. I have no urge to go and the CT didn't show that there was a blockage in my rectum or anything. I have a lot of medical problems (especially for only being 21) and take about 20-30 prescription pills daily so I worried about using certain products with them. It would be nice to just clean it all out at once, which the mag citrate used to do when I could take it but I don't know what to use anymore. If anything ever works, it just stimulates me once and I don't get very much relief. I'm not really eating much anymore, I'm very nauseous and sometimes vomiting. I DO NOT want to go to the ER or anything so if you have anything besides magnesium citrate or the usual "at home" remedies (water, fiber, fruit) please share!!