lump on face cause by pimple or staff infection?

hello... i had what began to look like a under th skin pimple with no head! however, it developed into a big infection that swelled my cheek all around and it was red and hot... after a fue days it came to a head and busted on its own. when that happened i helped it by attempting to push all the pus that was inside out of my face.... the swelling went down and the skin healed however i still have a hard dime size lump where the infection initially started.... what should i do? what could this be?