Dangers of wrestling for 14 year old boy?

my son had to be rushed to the ER before christmas due to urinating bright red blood. after evaluation, tests, etc., it was determined that he had exercise induced blood and protein in his uring...basically not getting enough hydration. he just started wrestling 2 months ago and has done very well. it's good for him emotionally, but this is his 2nd trip to a medical facility due to wrestling (the first was a sprained bicep) we thought might be a tear. i'm debating pulling him out. he no longer wants to do wrestling, but also doesn't want to look like a "wimp" to his friends. there are really only 3 more weeks, but they make the practice room extremely hot, don't push fluids, and i'm afraid more trouble lies ahead. any advice? don't want to make him a "mamma's baby," but this is very alarming to me. i'm an inch away from pulling him out early and just calling it a day.