Personally, I would wait until I was done with the antibiotics. Why throw good money after bad? Doctors don't get involved with the practical issues like cost. They don't keep track of everyone's insurance copays. All they know is that the patient keeps saying they are not improving, so they figure, "Let's throw this at it. What can it hurt?"
I'll say it again for emphasis. If you start and end multiple things all at once, you can't tell what is working and what is not. So, one change at a time, particularly when you are having such a difficult time figuring out what to do.
From the studies I have read, it does not cure either pouchitis or UC, but helps prolong remission. So, I seriously doubt it would change outcomes in a major way, but more in line of improving the management.
Jan