There is another antiviral medication called famciclovir.
It's a different medication than acyclovir or valacyclovir (Valtrex). There may be some cross-reactivity, but since you don't have a serious reaction to it, you might try it. Ask your doctor.
Some people get a lot of relief from using diaper rash cream for their outbreaks, and since yours is in the anal area, it might help. It's thick, and helps provide a barrier. Hemorrhoid cream might help, too.
When you can, leave it alone, and let the air get to it and let it dry out. Sleep naked from the waist down if that's possible for you, and after you poop, clean the area well - gently, with a gentle wipe or gentle soap, and then pat the area dry. If you live in a place that has bidets, use a gentle setting, and then pat dry.
Use the diaper rash or hemorrhoid cream when you need it during the day, when you're working or at school or whatever, and let the air dry it as much as possible at other times.
I hope this helps.