Pilonidal cysts are formed when hair is pushed up into the skin, leading to irritation and inflammation. It is not the same as an ingrown hair, because the hair is not originated inside the cyst, and may not even be attached to the skin (barbers can get pilonidal cysts on their hands, for example). Cysts extend as the hair is pushed deeper in the context of trauma or simple contact from sitting, riding in cars, and bicycles.
Pilonidal cysts commonly recur after drainage, and can present in several different ways. It sounds like two years ago you had an abscess associated with the cyst, which lead to the signs of infection such as weakness and fevers. Acutely infected cysts are best treated with incision and drainage. However, one half of pilonidal cysts present as a painless lump or draining opening. These cysts still require surgical evaluation to prevent infection and growth. Recurrence can occur despite excellent cleaning and hair removal
You should make an appointment to see your primary care doctor
for an evaluation and possible referral to a surgeon
who can discuss treatment options with you.