cracked fingertips

My 9 year old son has had a problem with peeling, cracked fingertips and very dry skin on his palms for about 4 years now. We have seen several doctors and tried hydrocortizone for excema and canesten for fungus and nothing has made any difference. Flare ups happen anytime during the year but is generally worse in summer. His skin in the affected area gets very pale with dark red sore skin in the cracks on his fingertips. It's really bad right now and  I am not sure what I can put on his skin for some relief. It's very painful when it cracks a lot.