I wouldn't wait to take her to the doctor. It could be a bladder or urinary tract infection, which are horrible, painful and itchy, but I would think she'd have some accidents and control issues if that were the case. It sounds like she's been spending a lot of time in the pool, which means she's probably been spending a lot of time in a wet bathing suit. She might have a yeast infection, which is also horrible, painful and itchy. I know I've experienced hot, burning urination with a yeast infection and I also know how miserable I am and how quickly I run to the store for medication. I definitely wouldn't make myself suffer a bladder/urinary tract/yeast infection for 4 days without seeing a doctor. She's had symptoms all weekend, please don't make her wait any longer to get checked out. Good luck!