I'm On Coumadin For DVT And PE, Recently Found To

I'm on coumadin for DVT and PE, recently found to be anemic and had colonoscopy and gastroscopy. GI doc wants to put me on Lialda, which I cannot afford, even with my insurance. My insurance will pay for Sulfathalazine but he says that is an "old medicine" which he does not want to prescribe. Can you give me some input on these two meds, and suggest how I might consider proceeding?