Wow, why would you use cortisone regularly? The rash is probably from sweating. Do you shower regularly? Using some corn starch there to prevent the sweating that is probably causing your problem in the armpits might save you some problems, as cortisone can cause a lot of problems. Mainly, at least in this post, you don't say why you think you have a yeast infection. Not to say it never happens, but men don't usually get them. I have no idea what's going on with you, apparently there are other posts, but not drinking water and using a ton of sugar like that can cause problems. If you work out hard at the gym, you sweat, and you should shower afterwards. Gyms also can be sources of infections, though not yeast, but other fungal infections from sitting on equipment someone else just sat on. Haven't been to one myself since covid, but to each their own. Anyway, you haven't described anything that would indicate a yeast infection, so post more info so you can get an informed answer.
Is this just not an extension of the question you already asked and had lengthy answers for?