What Causes Brown Spots In Between The Chest?

Im having brown spots in between my chests since a year. ive used many medicines and have gone to many dermatologists but none have worked. the medicines actually work for some time but the spots become active again after some time. ive used the following skin medicines :
Sautomet ointment
Eczemus ointment
Clobivate cream
Travacort cream
Please tell me what kind of problem this could be.and help me solve it. Please reply back as early as possible Thankyou.