Several members here have commented that their IBS started during/after a round of antibiotics, so that may be what has happened with you. Although it's nothing to really look forward to and we all dislike doing it, testing, however, would not be unreasonable. I know that it can be really frustrating trying to figure it all out. You'll get lots of information here on different ways that you manage your symptoms, ranging from taking calcium, adding fiber, hypnotherapy, food intolerance testing, etc. Lots for you to read up on! Good luck.