My leopard gecko has a blue triangle on its belly HELP!!! PLEASE!?

hes just a baby a few days old just got him... when he was playing on my hand i noticed a blue triangular shape on its belly so i did some reasearch and found that it could be impaction, crypto disease, or anything else i really need help i dont want to loose him(he also hasnt ate his meal today which i was a idiot and gave him 2 adult crickets one he regurgitated)