A few eels ago my fiancé felt a crater like scab on her scalp she payed not much attention to it seeing it was a scab and will fall of soon and heal. Today she felt the same scab and as she passed her fingers through her hair some yellow scab like particals came of. I took a look at her scalp and saw the same crater like scab turned into a bump about the size of 1/4th a penny and where the scab use to be an opening instead. I poped it like if it were a pimple and so much puss was coming out. I went on to doing it a little more and blood started oozing with the puss until it finally stopped. The crater like scab area stopped bleeding but occasionally specs come off it.should we be worried? Was it a cyst?