Have a doctor check your liver enzymes. All pharmaceutical products adversely affect the liver, and dark spots on the skin have traditionally been attributed to liver elimination, such as liver spots. There are natural liver cleanses you can use if that turns out to be an issue.
It would certainly be an unusual side effect if it were from either of these medications. Only your doctor can help you determine that by looking at the skin the color discoloration. Perhaps you should ask for a consultation with a dermatologist.