Suggest Medication For Sickness In The Stomach

My is 1 1/2. 2 weeks ago he came down with a cold. Then a week ago he started vommiting and not eating. I took him to the Er was told he had and upper resipitory infection, double ear infections, and a flu bug. He has only had 1 bowel movement in 2 weeks. has been sleeping most of the time and when he is awake he just cries, still not eating anything. He just tried to have a bowel movement, was screaming while trying, a little bm came out very hard. when I touch his stomach he screams in pain. Should I take him back to the er? or try giving him a laxative and juice?