hi, thanks for providing the brief history of your son. since you mentioned he had anemia issue and later he had lot of Respiratory issues as well. I think from my end this might have disrupted the metabolism and immune system which is giving him skim irritation over the spinal region. since the skin tissue near the spinal region is a bit thin and can get trouble easily. I can recommend that you could get your son do regular breathing exercises and physical activities. usually at certain times exercise can help improve the metabolism and immune system. once the immune system and metabolic system is balanced the chances for the skin bruises will be reduced. as for the betterment of the tissue functioning the oxygen is the major source as well. whatever medical could do with all things they are already trying. now you can focus in the natural way of improving the internal metabolism of body. certain times medical is directed towards the symptomatic and they help the best but at the end of every thing the human body is its own boss. and for making the body function better only need is to improve the metabolism and cellular functioning which can be developed by doing regular physcial activity. if any more information on metabolic exercises you can ask me. regards Jay Indravadan Patel