After having the flu for about a week, one morning I woke up and notice the bottom right corner of my lip was swollen. There was no pain at first, only a numb, swollen feeling of the lip. Until I squeezed my lip after noticing a bump then I start to feel a little pain. The day after I woke up and swelling was still there, this time it looked more like my lip was bruised. I never had any sexual intercourse or kiss in years. Nor have I ever had any herpes/cold sore outbreak. Not sure what was it caused by. All I remember was that I had the flu and this popped up. My throat and lips was a little dry when I had the flu. Before this popped up I notice I was grinding my teeth the night before which caused pain and discomfort to sleep. I had bought a Chapstick which I had never used that brand before. Not sure if it's an allergic reaction or because I bit my lip. Hopefully not a std. Please if you know anything tell me.View Thread