My son had an anal fissure, but although it is considered to be healed it is still very sensitive. It does make BM's more painful, and using TP also causes further irritation. We had trouble with the Cottonelle wipes, so my son uses unscented baby wipes (just don't flush them). He also uses a zinc cream as part of his daily routine (we like Penetin because it stays put, and doesn't migrate to the undies with body heat).
My son can also get cracks in the corners of his mouth, and is currently suffering from cracks behind his ears (although those are almost healed now). We have found that a zinc supplement, and applying olive oil topically works best for these areas. I don't know if these skin problems are same type of skin issues he has on his bottom, so I would definitely check with the doctor before considering putting olive oil anywhere near the genitals.