I Have This Skin Condition Where Dark Spots Appear Mostly

I have this skin condition where dark spots appear mostly on my back. I started to get them when I started puberty. It doesn't irritate me at all. At first I was told it was a fungal infection but two of the three creams suggested did not work. The third cream didn't intirely work, but it made the spots light. After going to a dermatologist I was told it wasn't an infection and the reason the cream appeared to work was due to a steroid that was present in the cream(lotrazone). Decades later I was given a cream that had betamethasone and it cleared my skin in about three weeks. It stayed clear for about two months before it slowly came back. I was wondering is there another way I can keep my skin from getting the spots without a prescription or is that my only option?