Ugly fingers!!!

Although I've recently quit the bad habit, I've been a nail biter for most of my life (I'm 18 years old). My nails are growing and my cuticles are looking nice but there is one problem that I am worried about. The skin on the upper joints(DIP joints) of many of my fingers are bumpy and thick (like a callus but softer). They don't hurt or cause any problems except for the fact that they look swollen and ugly. I don't know if they are there because of my nail biting problem or from a medical condition.