Thanks for your question on Health Care Magic.
I can understand your concern.
By your history and description, possibility of either
malunion or infected
hematoma is high.
Since you had trauma over your leg, possibility of minor bone crack or hairline
fracture at that time is high.
Without proper treatment, fracture heals by malunion. It is not perfect healing. It is faulty healing. And this can cause swelling and pain afterwards.
Another possibility is infected hematoma. All
injury causes blood accumulation at the site of injury. It produces hematoma (dead blood). If it is infected, it can cause swelling and pain.
So better to consult orthopedic doctor and get done clinical examination and
ultrasound examination of local part for the diagnosis of your swelling.
Hope I have solved your query.
Wish you good health. Thanks.