You should see your primary doctor - or try a general medicine or GI forum
I would think the Gastro forum would be your best bet.
That said, I experienced this before (and for a period of time) that occured after a few round of antibiotics. Perhaps the meds had nothing to do with this. Anyway, my then Dr. recommended I "flush" my sytem out.
Take the fullest does of Milk of Magnesia, followed by a full glass of water just before you go to sleep for the night. Do this two nights in a row.
I did this and the next morning...wow, spent some time on the potty! lol For about a few days thereafter, I did feel "tender" but then, it went away. Just like that.
My husband was also experiencing some abdominal pain, had him do the same...and sure enough, problem resolved.
This may not be your findings but it is something you can try, without a Dr. visit or Rx.
That said, if you are on any medications: make sure that it is alright to take Magnesium.
~Kate