The symptoms are suggestive of pilonidal cyst. It is a cyst right over the coccyx area. In this the skin becomes reddened or even sometimes discharges pus and blood. When it is infected, it causes pain. Antibiotics or surgical drainage may be required.
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.
It is a little painful but I have experienced it three times in my 50 year life if you use vinegar while in the tub I actually put the vinegar on a towel and put the towel in the crease of where the cut is it is painful but it's worth it it takes away the sting and I use the Summer's Eve feminine wash that way you can keep it clean that the skin is excessively dry there so it splits I realize that it's only when I'm on the go and I'm bathing trying but not putting lotion on my body as I would in my everyday maintenance of myself so the skin splits plus I am a plus size woman I hope this helps but I guarantee you vinegar works