Hello, I have gone through your query and understand your concern. I suspect you have Sebaceous cyst also called epidermal cyst. This is mostly seen is hair rich areas like scrotum, scalp etc. It contains the white cheesy substance as the one you had on prick of the swelling. It is not advisable to prick or cut open the cyst. Because it get infected. As you have applied antibiotics nothing to be worried now. It may develop later and it should be excised completely by surgeon. Hope this helps. Please write back for further queries. Wishing you good health.