My Russian tortoise looks like his skin is kinda peely and he sneezes a lot, should i be worried?

also the outer part of his shell looks abit thin. He's well fed, eats lots of leafy greens squash and other veggies with and occasional strawberry. and i used the calcuim powder I let him soak in water every few days for about 25 minutes, he has all of his heating and light needs, im worried hes my baby ):