Pimple on lip

I get cold sores every now and then and they always pop up on my lower lip. Today I woke up and noticed a pimple on my upper lip. Looks different from a cold sore. I popped it and the little white head keeps coming back. It doesn’t really hurt but of course it’s unsightly. Not sure what it is or what to do. Online search really leads me nowhere because all the articles say it’s a cold sore. Maybe it is but it looks different feels different and is a different place. I was just ovulating and expecting my next period around the 30th. I did get a bad sunburn two weeks ago too. Don’t know if that helps. Any info will be appreciated. Tia.