Baby not eating

Currently I have a 3 month old who simply won’t eat. He used to drink 6 oz every 4 hours and now we can barely get him to drink 3 oz every 6-7 hours. All he wants to do is sleep and when he’s up all he does is smile and laugh and play. We’ve tried everything from burping, switching bottles/nipples, cereal/ non cereal, ready to eat formula and he simply will not eat. We even tried a windi yesterday and it wasn’t gas or constipation. Our pediatrician recommended pedialyte and he hasn’t drank anything of that. Does anyone have any other recommendations that worked on their baby? Or if they’re going through the same thing?