Know any medications I can buy for erythrasma?

Antiseptics. This is rather chronic, superficial skin infections often occuring in the skin folds areas. Topical antiseptics such as peroxide/manganate, rubbing alcohol (burns quite a bit), or not commonly thought of is hand-sanitizer. Benzoyl peroxide cream may help. It is important to keep dry/clean. May need topical antibotic script from doc and oral meds needed for severe cases. Good luck.