What doctor should I see for my lumpy lip after my lip injury? (Photos)

Swelling after lip repair is very common and can cause asymmetries that are firm to touch and distressing to patients.
I discuss with patients that have had laceration repairs that scars can look worse before they look better.  Swelling and scars can peak around 6 weeks after the injury and then will usually continue to improve over the next 6 months to a year.  If you had a lip laceration repair and then a subsequent fall and injury, this could've reset the clock on swelling so to speak and slowed the whole process down. 
Most Plastic Surgeons will wait as long as possible prior to revising a scar.  I personally prefer a minimum of 6 months, but 1 year is better.  This allows all of the swelling to resolve.
Other contributing factors could be granuloma, or scar nodule formation, around absorbable sutures that were used to repair deeper layers of the lip.  These too can soften or resolve over time.
The long and the short of it is that this will probably get better given time.  It's challenging now, because you have to live with it and watching swelling resolve is like watching water boil.  If it doesn't improve to the degree that you'd like, it would be reasonable to seek an opinion from a board-certified Plastic and Reconstructive Surgeon.
Good luck!