Ok, he's got trips or a full house. He could have trips or even two pair and bets because he wants to slow you down, he bet now and don't have to call another bet on the river if unimproved, if makes his boat he will earn one more bet (cause you will at least call the river). But if you raise and he reraises, are you gonna throw your hand away? It will just cost you the same amount to see the hand thru. So why complicate things?
Call him down.