What an ugly situation for a nice starting hand. Not knowing your opponent, I'll assume like you that he is raising a big pocket pair. If we give him that, and he raised J's, there is an argument for a fold on 4th. When the K hits him on 4th, there are 7 combinations of high pocket pairs that beat Jacks possible. He could have the case Qs, in which case you would have an easy call. There are three combinations of Ks he could have in the hole, which leaves you virtually locked out. There are three combinations of aces, which leaves you in a very bad spot. Regardless, you are trailing little once or trailing large six times, and if you wanted to dump it on 4th street, I would have no complaints.