My 6-year-old son is experiencing very painful urination immediately after swimming. It does not matter if he is swimming in a pool or the ocean, it's the same either way. This first happened about a year ago, and has occurred every time has has swam since then (which has only been about five times). The first occurrence happened about an hour after he was out of the water. But for the last two occurrences, he began experiencing pain after being in the water for about 15 minutes (ocean and then a few days later at a pool) and it was so bad he was crying. After he urinates the pain subsides, but when he initially starts to urinate the pain/burning is so intense he screams. He does not have problems with pain or urination at any other time, and we go months and months without swimming but each time it's the same problem. We've tried having him urinate right before he goes swimming, rinsing off as soon as he is done swimming, etc. There is no blood in the urine, no foul smell, nothing abnormal looking on the skin, etc. At first I thought it was a reaction to chlorine, but since it's happening at the beach too, I'm at a loss. Any suggestions on what it could be? Thank you!