The symptoms you have mentioned suggestive of a hematoma. It is nothing but a collection of blood under the skin following a blunt trauma. You don t need to worry regarding this as it will subside by it own even without treatment. You can take simple analgesics like ibuprofen or diclofenac for pain. Apply ice packs over the affected area for symptomatic relief and fasten the recovery. You can also try anti inflammatory drugs like seratiopeptidase for decreasing the inflammation and to reduce the swelling. Most cases resolve in few days with these measures, if the symptoms persist despite all these take an X-ray to rule out minor fractures or contusion.