I've been having this lip problem for couple months now.
I am a 21 year old female-- usually healthy, no allergies except Penicillin. Since October of 2015, I've began to have some dry lips-- not chapped but they felt dry most of the day. I started using Burts Bees chapstick and EOS to help it. Some days it worked and other days, not so much. After couple months, beginning of November of 2015, there was a slight pink bump (not a cold sore, no fluid inside) on my lower lip. The next day, the bottom lips were swollen. They weren't severe but definitely a bit swollen. I took allergy medicine to see if the swelling will go down. It did later on but the bump was still there. Couple days later the swelling would come back and there would be pain (burning and later itchiness).Whatever food or even toothpaste that touched my bottom lips, it would burn a lot. One day there was even crust only on the lower lips where the bump was. Sometimes it would feel like it was sweating, or fluid was coming out. I don't think it was pus because the fluid wasn't yellow.
I've started using Vaseline to soothe the pain. I also visited my university's health office. They couldn't find out why but prescribed me to Nystatin Cream USP. I thought it got worse after applying this for several days. I discontinued it and went back to my Vaseline.
After couple weeks, the bump disappeared and there was absolutely no pain or burning sensation, or even itching. However it came back when I caught a cold. After I felt better, the bump and pain would go away.
Fast forward to now, it came back again. This time it would not go away-- the Vaseline doesn't do much now.
-I've stopped using EOS because I thought that was the cause, but nope.
-I've also changed toothpastes but that wasn't the cause.
Sometimes the itching would occur around the side of my mouth too. I don't think it has to do with the weather because I've never had problems with chapped, dry lips.
What could this be?