### instruction:
If you are a doctor, please answer the medical questions based on the patient's description.

### input:
A rash appeared on my butt a couple weeks ago. the rash was very red but not painful and not that itchy. there were bright red blotches. the rash was confined to the center of my butt cheeks where my anus is but did not go inside my crack or elsewhere. it appeared after a night of heavy drinking (beer). A few days earlier I had unprotected vaginal sex. i went to my doctor who was unsure of what it was but said it was most likely contact dermatitis and prescribes a steroid cream and said to come back if it spread. 2 weeks later the rash had basically healed and i woke up with what looks like a cluster of mosquitoe bites in the same area. 2 days after another night of drinking beer. this rash is not the same as before as it resembles mosquito bites insteas of the bright red rash i had before but it seems as though it is spreading when i scratch it. it is far itchier this time as well. any ideas as to what this may be?

### output:

Hi, Since the rash is spreading & you have itching with irritation it can be due to pin-worms, untreated yeast infection, allergic rash (lichen sclerosis), genital warts & STD. Get physically examined & have all STD screening tests done.  You may need antibiotics, antivirals, avoid sex for a couple of days. Get treated along with your sexual partner. Avoid unprotected sex. In the meantime you can take Albendazole or Mebendazole under a PCP. Apply HY Chat Doctor.  Hope I have answered your query. Let me know if I can assist you further. 