I Have Ulcerative Colitis (radiation Colitis) And My Doctor Was

I have ulcerative colitis (radiation colitis) and my doctor was giving me samples of a great medication for 1.5 years (Lialda). Then, the generic came out - Mesalamine DR 800MG. I cannot afford either one ($375 to 600 a month. So, I'm doing with out. Have episodes about once a week, spending lots of time in bathroom. Is there any way I could get help getting one of these meds? I'm 76, and live with my grown daughter and so-in-law and 5 kids. I get $15,000 a year medicare