Good day everyone! Girls, could you please tell me what this rash is? …

Good day everyone! Girls, could you please tell me what this rash is? My son first got it on his back and chest, it lasted a long time, then it would disappear. Then it would reappear. Now it's popped up again on his chest, stomach, and spread to his sides. Besides that, there are white ring-shaped spots on his tongue, like blisters, we were prescribed Holicol gel for stomatitis. It’s slowly going away. The child has become restless, constantly crying, even not just crying, but screaming. I have already read that these are symptoms of leukemia and other crap. We are going to the doctor in a couple of days by appointment. For now, help with