Hi and welcome to HCM.Pilonidal sinus
is unpleasant lesion which usually persists and have phases of inflammation and improvement. the best treatment is surgical,actually the only 100% succesful one. Till surgery it can be treated by antibioitc and topical creams but it almost always recur so people usually decide to perform exscision of sinus under general anasthesia.
Wish you good health.Regards