I suffer from constipation IBS. And had the same problem following my op. Endometriosis had stuck my entire tummy together. In my case it was found that my pain following the IP, was caused by constipation and was given enemas and lots of laxative in hospital. It did eventually settle down again. My period was the only time my bowels worked properly.
If after a few more weeks, everything doesn't settle. I would suggest that you ask to be referred to a consultant to rule out anything more serious. An IBS diagnosis is one of there being nothing serious the bowels are just mucking about. And, unfortunately as I know to my cost, the diagnosis doesn't lead to a cure, just a lifetime of drugs and crossed fingers (whatever the TV ads say).
I hope that this helps.