try cutting your sodium, cutting your wheat, cutting your carbonated beverages, and using a mild anti estrogen and some herbal diuretics.
it might just be water retention.
i know that when i finally got down to a low boy fat %, i thought that i was doomed to never see my abs clearly because of what i thought was 'thick skin', but i tried cutting my soddium and upping my broccoli (natural anti-estrogen) and my abs got pretty clear in a few days.