Hello,
The symptoms are suggestive of a pilonidal sinus. Pilonidal cyst is a cyst right over the coccyx area.I n this the skin becomes reddened or even sometimes looks like a small bruise. When it is infected,it causes pain and may drain to form a sinus. Antibiotics or surgical drainage may be required for which you should consult a surgeon.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
Possibly a pilonidal sinus.Do consult your doc.