Random bleeding while playing around

So the other day my guy was fingering me. Nothing new, nothing stretching anything much... I did feel very wet but just thought he was doing a good job.. then he leans up saying, “babe, your bleeding” I BLED ON HIS BED. This was not one drop but like 4 quarter size blood spot on his bed & all over his hand. I quickly got up to wash myself & then back to his bed. He was chill about it saying it was okay & nothing to be embarrassed about. We checked his nails that were cut short, nor did I feel anything sharp or hurting during the whole process.

This was weird because I was on day 15 of my cycle & normally my cycles have been about 50-60 days. I never spot unless it’s around day 30 but very rare if that. Also, I’m 23 so it’s not like started menarche to give some background.

Any idea what caused this?