Hi With your query, as you mentioned that you have impacted tooth that means the tooth hasn t reached to its occlusal level and still covered by gum that is technically called as pericoronal flap. Coming to your swelling I mean the lump could be a pericoronal abscess which may be due to forceful food impaction in to gingiva called as pseudo pocket. Treatment for this are by two means initially it has to get irrigated by an antiseptic solution then either you should go for a procedure called operculectomy which means removal of gingiva or gum that is present over the tooth. This decision will be made by examining the tooth eruption status by radiograph and your age. In some instances if they decide tooth development is complete and chances of recurrence is more then you may have to undergo extraction for the impacted tooth. I would suggest you to go and visit oral surgeon for time being you can start using antibiotics along with pain killers and visit dentist as early as possible for complete treatment.It is unethical to prescribe antibiotics without knowing your drug history and medical status.Hope this is informative