HELP PLEASE

i had an ingrown hair around a week ago ( ignore it because they usually just go away for me ) but 2 days ago i lt was still there and i noticed a BALL under my skin and now it is going up towards my stomach and today the ball is dime sized with swelling. what is happening ?? is it a cyst? what should i do?? it hurts very bad and i am concerned. ( it is on the top of my pubic hair )