Help!

I know this is a pediatrician matter, but I need help until I can get him in. My son is 3 1/2. We are still in the potty training phase. It’s been rough. Lately he has pooped a whole lot less, volume wise. But a whole lot more frequently. It’s never a formed poop. Almost a peanut butter consistency. The past two days it’s been an all day thing. I’ll change him and not even 5 minuets later he’s pooped again. It doesn’t matter if we’re in underwear or pull-ups. I’ve put him on the potty and he will sit there forever. He pees fine on the potty. I’m worried something may be wrong. Constipation? We’ve went through a whole pack of pull ups in two days because of this. I’m going crazy.