TweetKeeping it simple. If you do have any access to a dermatologist, a very very inexpensive RX is Cleocin lotion. It is a topical antibiotic.
If you do not have that access, DO NOT OVER CLEANSE. Use Cetaphil Cleanser (either the liquid or the bar), after toweling off, swipe the area with good old fashioned hydrogen peroxide.
Get a salicylic acid cream to apply to the area -- Clinique makes a good one. Use the salicyclic acid (which is a beta-hydroxy) one day -- and a regular benzoyl peroxide cream the next (alternate them). And be careful -- it will fade some fabrics so make sure it is dry or wear a white tee shirt.
Make certain to not use too much detergent on your clothes. And shower as soon as you can after the gym. If you cannot, get yourself some wipes (facial wipes or baby wipes) and wipe down the affected area immediatley.