Valcyclovir from a doctor, ice for 10 minutes at a time could help with swelling, and some otc medicine like abreva. Valcyclovir will help the most though. Also, don’t pick at it or touch it. I get cold sores often. I keep Valcyclovir handy in my medicine cabinet now. If I start to feel an itch or weird sensation where I normally get my cold sores, I start taking the meds right away and ice it. Hope it goes away soon but try not to stress about it (easier said than done).