How are you controlling your heat pad, and what are you using to measure the temps?

And what is your humidity when she's not in shed? Is it always kept at 80-90%?

I will echo the others, you really need to get her seen by a vet and get treatment. In the meantime, I'd switch her to newspaper and keep it dry. A water bowl on the warm side or in the middle should offer her enough humidity. I use newspaper and my humidity stays 50% at all times, I don't bump during a shed and I have perfect sheds.

Is her enclosure a tub?