I totally understand; I relieve the receptionist when she takes her lunch or is on vacation and I hate being tied to the phone while I'm having a bad day (luckily those aren't too many anymore). My finance is a tech for a large computer company and I have thought in the past that I could never work there because what do you do when you are on an hour and a half long call installing someone's operating system and you're having diarrhea? He's been having some issues of his own lately, but luckily he's doing web part orders now so he can get up and go as often as he needs to without putting anyone on hold. But of course you are probably like him and have quotas to meet in terms of calls taken, and that can be hard to do when you're in the bathroom so much. And big companies like their quota numbers better than they like their employees, I think. If your doctor does end up diagnosing you with IBS, you may want to get her to write a brief note (addressed to your HR manager) saying that you have a bowel disorder that is pretty untreatable and that you may have to be excused from work to go to the bathroom frequently. And then give this letter to your HR manager (keep a copy for you) to at least put on record in your file that you have an ongoing medical condition and that can explain why you don't meet your quotas all of the time or why you call in sick as much as you do, etc.
Some people have been fired or pressured to quit their jobs because of their condition. It's best to be prepared in case that happens by establishing to your HR that you have a medical condition. That way they can't claim later that they didn't know you were sick and that they thought you were just a slacker. And of course if you don't tell people bluntly that you are sick, then how are they to know that you are not taking calls or missing work because you're sick? But, by being able to prove that you notified your HR director of your condition, you may be entitled to protection under FMLA--which means they can't fire you for taking time off for a medical problem. Also, establishing in advance a medical problem may allow you to get unemployment benefits, whereas they are not obligated to give you any if they say they fired you for underperforming (you can then prove that you underperformed because of your illness). And lastly you have proof that you can't hold down a job due to your condition, which may allow you to get disability. There are a few people on here who have IBS so bad they are on disability. But all of that hinges on you establishing and documenting your illness in advance. So you're just going to have to face telling some people that you have something wrong with your bowels and sometimes it sends you to the bathroom frequently. I think you'll be surprised at the number of people around you who can sympathize. In my office of 20 or so people, there's me with no gall bladder, another lady with no gall bladder, one with IBS and one with a stomach ulcer and bowel problems as well. So I can always find sympathy.