My bottom lip is swollen on one side. i used to bite my lip. i stopped now, but the swelling from before won't subside. it's been a couple years.

Mucocele: Mucocele is a fluid fill cyst causing by depostion of fluid from minor salivary gland into tissue space. It could be very easy removed by resection (a simple 5 minutes procedure). It occurs as the minor salivary gland is injured during lip biting. It may have blue tint color.

Seek a dental eval: Your brief hx stated that you have a lip swelling that was atributed to trauma from a biting habit. Unfortunately, one can develop a fribroma from trauma. A benign fibrous lesion that leaves the appearance of swelling. Please have a professional evaluation to rule out any other potential underlying issues.