How To Prevent Recurring Blotchy Areas On Back And Stomach?

My skin on back and stomach has been blotchy for a few months now, i was told by a doctor that it might be stressed related and i was given medicine (i don't remember the name but she said it was similar to Lamisil). Now the blotchy areas are getting darker and my skin looks like it is stripping. Is my skin getting better or do i need to go back to the doctor because its getting worse? Are there vitamins i could take so that this doesn't happen again?