//////in that it doesnt hurt (much) when fingers are pressed into it, but really hurts when theyre pulled out quickly.//////
First of all, the above description is NOT "classical " rebound tenderness and doesn't indicate any peritoneal irritation in your original post,
Rebound tenderness is elicited by the "flat" of the hand NOT the fingers. An important diagnostic difference.
Your pain could be due to many things,but from your OP I would suggest that a cyst has burst or even bled.
At the moment no big deal, but monitor the situation for the next few days.