Pnemonia, ear infection, and now has trouble walking

My son has had trouble with coughing and congestion and fever. After my older son almost was admitted for pnemonia and a sinus infection, I decided maybe my 1 year old should be looked at for these similar problems. The doctor looked at him and determined he also had pnemonia and an ear infection. He was on Bioxin for 10 days and breathing treatments and appeared better. As soon as he got off the Bioxin he got worse again just as my 3 year old had. So they put him back on a stronger antibiotic and his cough, congestion and fever disappeared again. While he was on the antibiotic he was very dosile and napped a lot then after a week on the meds. He started limpping. His legs weren't working right and so after two days of this I stopped his antibiotic a day early. He seemed to feel better for the next 24 hours but then started the coughing and congestion again that night. Now he has gotten up this morning and can barely walk. His hip on his left leg does not want to bend and he keeps coughing even after breathing treatments and Pedicare cough medicine. I have given him the herbal sniffle and sneezes that is also good for cough and toddlers echinecha. I am worried about the muscle problem because when my 11 year old was 5 he was sick and even after antibiotics had troubles walking. I took him into the Dr. and he said it was strep arthritis and had me give him Advil. About six months later after having blurry vision I took him to a optomologyst and she saw a cataract that she said was formed from the inflamation from the arthritis. He still has vision problems today. I don't want that to happen again- not to anyone. If anyone knows what this could be let me know.