Im worried about something...Help!?

(Im using my brothers account so thats why it says his name) My vagina is aching. Not very bad but it throbs. I just turned 13 yesterday so I masturbated for the first time. I didn't use anything big. Just the neck of a coke bottle which was 6 inches in length. and 6 inches in girth. It felt really good at the first 3 inches or so, so I jerked from the pain and the jerk made it go all the way in, then it stopped hurting. I spent maybe 20 minutes masturbating when it started feeling extreamly good for like 9 seconds and then some kind of liquid went into the bottle from my vagina. Itwasn'tebecausetdidn'te from my pee whole.. What was that stuff? So I pulled the bottle out and seen that there was blood on it! Im really worried nowbecauset throbs. Do you think I cut something? Should I go to the doctor? Please help!