My Son Will By Three Next Month. He's Still In

my son will by three next month. he's still in diapers and pull ups. But it's not the potty training issues I'm most concerned with. He's had a rash for several WEEKS now. He's our third child so we thought we'd seen/heard just about everything. But this is really worrying me. Dr. gave us yeast infection cream and we've tried just about everything they make. I;m worried bc this seems to be going on way too long