This sounds like what my husband experienced in the hospital after his surgery to remove rectal cancer. They finally believed him (after he was projectile vomiting ileos fluid from his stomach). They put in an NG tube which suctioned out all of the "crap". That lasted about 36 hours until he pulled it out in his sleep. The only remedy that seemed to help was more frequent movement which finally "woke up" the bowel and things started to move again.
Your problem is way past surgery stage so it does sound like scar tissue or something is blocking things up. Follow the advice of those who know WAY more than I do and get a second opinion, or third, or fourth if necessary. As for the work situation....under FEDERAL LAW, you are guaranteed 90 days of Family Medical Leave within a year. They cannot fire you if you do the paperwork to request FMLA and have a doctor certify your need to be off. Believe me, as the wife of someone fighting cancer this is something I have researched!
Sending up prayers for you. By the way, not sure where you live but my husband found that medical marijuana helped him deal with the pain he experienced during chemo and radiation. I know not everyone agrees but just letting you know it did help.