It seems that you have most probably suffered a sprain
over your ankle. This may cause swelling of the soft tissues around your ankle. The absence of swelling is a good sign which may infer that you do not have a fracture
You may start by using some over the counter pain killers or analgesics. Aslo applying ice over it may roduce some relief. While sleeping you may palce ur foot on some pillows. Also wearing comfortable and loose footwear, avoiding weight bearing on the leg and some rest for the foot can help resolve the problem.