I don't think that you need to be worried about doing anything for your kid right now. From what I gather it maybe because of exposure that there may have been discolouration. Please be reassured and leave it alone if the kid is otherwise healthy. Over a period of time as he sheds the old layers of skin and forms new layers I am sure his colour will revert back to what it was.
Please give it a little time as he is still an infant. I don't think anything needs to be done at the present time. But still if you are worried it would be better if you could get him examined thoroughly by a nearby paediatircian or a plastic surgeon.