Do I have a yeast infection?

Sometimes after my period (about half the times) I feel this diaper-rash like sensation from wearing sanitary pads all week (doesn’t really happen If I wore tampons all week) and it goes away about 2 days after my period. After my period this time, I felt the same sensation but it continued much longer than usual (4 days at this point) and I started noticing I felt it specifically on one side only externally and it looks a bit red but nothing to crazy. I didnt feel any pain or burning when I peed but then I peed in the shower and it burned only as it passed over that side where the irritation is. The kind of burning sensation really started to bother me so I concluded I must have a yeast infection, I bought cream and started applying just to the irritated part yesterday can thought the instructions say to apply internally also. I’ve never had a yeast infection so I just wanted to know if 1. This sounds like a yeast infection? And 2. Should I be applying internally as well even if I feel no discomfort? Or is it ok to continue to just apply to the irritated external area? Thank you for your help! I just moved states and have no doctor yet and the soonest appointment I could get was a week from yesterday so I just didn’t want to wait to test because it was starting to bother me