I think your uncle has a diabetic foot ulcer as inidcated by the skin coming off and also reactive node which is secondary to some sort of infection . It is very important that he needs proper care, with out which he is likely to end up with further complications He would need to be seen by a physician specialised in diabetic foot problems as he would need debridement, dressing , off loading and treatment with anitbiotics to get back to his normal.