You haven’t mentioned whether it’s in a single tooth or is it generalised. It looks like there Is issue with the area under the teeth. Which could be due to decay in the tooth or traumatic biting.
Next Steps
Visit your dentist, he/she will advice a x ray, that will decide the further treatment plan.
Health Tips
Taking mere antibiotics won’t help in most of the dental problem, avoid unnecessary usage of antibiotics. Your tooth requires definitive treatment.