I've had my turtles for seven years and while I put them in shallow water tanks for feeding and sleeping, I let them roam around the verandah for more than 4 hours every day. The air here is very humid and the weather temperature is around 27 deg celcius to 33 deg on hot days. Their shells peel sometimes but we assumed it was shedding. Three months ago, the situation got worse when their shells peeled more excessively than usual. I also noticed white patches possibly fungi on the shells. Could it be shell rot?
Please respond as I'm very worried and there are no herp vets in my city! The turtles are still active and eating normally.
One of the turtles' shell is kind of peeling out in a fan shaped way as well!

Thanks so much!