possible blood vessel or vein?

ok i decided not to be a pussy and go for a delt shot in the left one.
i stuck in dart with no pain, asparated with no blood... then i pulled the damn thing out slowly as i aways do and all was fine until the dart completely left my shoulder. blood just started pouring out and it was some dark shit, almost purple. it fuckin hurts now i hope it doesnt too much tomorrow. ive been rubbing it all day and i dont know what happened. this has never happened to any other body part except my delt. any ideas and any remedies to keep pain down? i have a heating pad not sure if it was a good idea to use it on that. lemme know
thanks alot!

its the day after my injection and my shoulder only hurts liek the normal day after pain. not too bad. i just dont know what the fuck made it hurt so bad yesterday. when u inject a new site does it actually take some getting used to? today i shot right glute andi asparated, no blood, then when i shot in the last bit of fina is sucked some blood up and then i got a real bad fina cough for the remainder of the day. dunno how that works.