Hi! I Have A Sore On The Skin Just Under

Hi!
I have a sore on the skin just under my bottom lip that's bothering me. I don't think it's a cold sore - it didn't feel numb or tingly before popping up. (My fiance does get cold sores. He had one the last time we saw each other, but didn't kiss.) It just hurt like a painful pimple coming in and had a whitehead like a pimple too.
It's been about a week and the whitehead has gone away, but the spot is still red and swollen. It throbs occasionally, otherwise has not gotten any better or worse. I wash it twice a day and use acne medication at night (2% Salicylic Acid), which has dried my lips out a lot. I have gotten a zit in the same area before, but it didn't take this long to go away.
Any ideas/help would be greatly appreciated. Thank you!