Thanks for writing to us.
Sounds like you have a cyst
. It could be from an ingrown hair or a block hair follicle or even a pimple. Apply warm compresses to try and bring it to a head so it can evacuate. If it does not in a couple of days you will need to go to the doctor and get it lanced. Once it ruptures the pain goes away almost instantly.
Try to sit on soft cushions so you don't bruise
it further and cause yourself more pain.
I do hope that you have found something helpful and I will be glad to answer any further query.