Mystery Itch? Help!

Went to the doctor last week for a possible sinus infection. It turned out to be allergies, but I was prescribed amoxicillin just in case. It did nothing for me, so my doctor told me to discontinue it. This was all happening during my period. Two days ago, my period ended but I woke up with a super itchy clit! It feels like a yeast infection but there is no discharge. I'm only itchy on my clit and nowhere else. My clit is also red and sore, but I haven't been intimate in a few weeks, so that can't be it. I took a monistat brand test to check and it was negative for yeast infection. I put the anti itch cream on and it didn't help at all. I bought the monistat medicine cream and put it on anyway. I'm getting some relief. What do you think this is? An allergic reaction to the amoxicillin? And how do I get rid of it, or do I just need to wait until the amoxicillin is totally out of my system?

Thank you for reading. ❤️