do you play with him? my boy used to attack my ankles, back when i first brought him home. turned out he was bored. got a bunch of interactive toys and started playing with him and he mellowed out nicely.
this is, of course, assuming that he’s clear of any medical issues. he’s been to the vet recently, right? 🙂
he sounds like he might have bloat. can you get him to an emergency vet?
If he is with you need to find an emergency vet near where ever you are as soon as possible, this could be bloat, or a blockage. Both situations are life threatening. If he is at home you need to have whomever is watching him get him to a vet.