my 7.8 year old son has had a constant weight of 20 kg and height 120 since 4 years and I have tried many vitamins and exercise n food but he is not gaining weight and height please help me out

A. Since four years if it has been like this then that’s quite a matter of concern see I would advise you to have a full body check up an evaluation with your doctor whatever details analysis is required because on the basis of that report only further things can be suggested