It may well just be normal post surgical stuff but I would get into see the surgeon as soon as you can. I had an undetected leak shortly after my takedown which I let go. I suspected a fistula but it wasn't actually diagnosed till a year later. I wonder if I had been on antibiotics early on if I could have avoided it. But I really don't know. I also don't know if a fistula would show up on a barium enema. I've had three MRIs that don't show the thing and I have stool in my vagina.
I certainly don't want to put you into panic mode cause that sure doesn't help. but I really do acknowledge your concern. You have every right to ask for prompt investigation.