Quote Originally Posted by dragondawg
It's quite unclear what if any growth would occur as a result of not neutering. An un-neutered male is more likely to develop benign prostrate enlargement, but no relationship to bumps/lumps on the rear. Cockers are however genetically prone to Histiocytomas which is usually a benign tumor that stays localized. Presumably the Vet has sent a needle aspiration of the growth off to a Pathology lab? If not then have them do it.
That's not entirely true. He could have testicular cancer, which is not uncommon in unneutered dogs.... It COULD be a histiocytoma, but it could also be cancer or another type of growth.

As for the rest of it, I would have him evaluated by a vet, if you haven't, to address his allergies and ther growth. As for the rest of it, well just help him enjoy the rest of his life as best you can.