It's been a while since their post, but I thought it might be helpful to them still and to any others with similar problems.
Concerning a rash under the breast and around legs where underware elastic goes, I've had a similar problem off and on since diagnosed w/ diabetes. It was not an allergy but actually a fungus which had developed. It was annoying and painful. Nothing got rid of it. My doctor (general and dermatologist) both prescribed Zeasorb power with Miconazole Nitrate 2%. There is a Zeasorb powder without the antifungal, but don't mistakenly get it because it won't really help. You have to kill the fungus and then keep the area dry.
They say this can commonly happen to diabetics because our defenses are not really strong enough to ward off the fungus.