I've also seen this kind of look with a stuck shed but I agree if you can feel something inside of him that large the a blockage does seem most likely.
I once managed to get it to the vent and then break it up using a spoon to ease one of my females through it but I can totally understand if you would prefer to have a vet do it as urates can be very hard to "break apart" and it is a very sensitive area for the snake. Should you try and do it yourself I would advise two people so one could restrain the snake and another work on it over a large container. But a good herp vet should be able to deal with this far better than a normal owner with a pair of needlenose pliers. :/