Swimming when the water feels cold

I have an 11 year old daughter who is an excellent swimmer. She has been sort of diagnosed with ADHD, Anxiety and maybe something else. We are looking into all of this more thoroughly now. It all started when she got sick with a fever for about 14 days in the middle of summer swimming. At the end of the 14 days we had blood work done and it showed she had the mono virus in her system from a month or two earlier.

Anyhow, after this she always thinks the water feels cold and has a very hard time swimming enough laps to feel comfortable. We seem to have some good days when the water seems to warm up quickly to her and she will swim a great practice, but then we have days when she jumps in(since her pediatrician said she had to just jump in) and will swim 2-4 laps and the water still feels cold. If this is the way it happens, she starts crying and doesn't know how to make herself keep swimming. How can I help her and does this sound like anything you have heard of?


Thanks
swimmom