What Causes Severe Cramps, Loose Motion And Gas Problem?

husband had athird of his large removed almost 4 weeks ago,surgery went well and was released after 4 days.a few days at home pain increased,went back to hospital and readmitted. blood tests,catscans and x-rays all came showing no problems.still in hospital for almost 3 weeks,still having severe cramping.he is passing some loose stools and gas.how long should this take to recover.worried wife.