Make an appointment with a surgeron...he can test for a hernia. I had the same problems that gradually got worse over the years. Come to find out, I did have a ingual (SP?) hernia. Surgery/recovery was a breeze. It definately helped get rid of that pain. Now if I could only get rid of the adbominal pain.
You'll have to return to your doctor if the water doesn't help. Too many times, we patients take the intial doctor's opinion as the gospel and quit seeking answers when the first treatment doesn't work. In today's medical world, you have to keep going back and back and back again, or find a different doctor to do a more in-depth examination.
As for your hernia question, it's worth looking into. Do you have increased pain when you lift heavy objects or cough hard? If so, that would make it more likely that you're on the right track with a possible hernia. The problem is that there could be other things going on in your intestines causing your symptoms. All you can do is keep talking to your doctor or find a different one who is more aggressive in figuring out the cause of your symptoms.