Lookout, I wasn't aware that Sheila had damaged herself at the party -although I believe that at some time she cut herself when she smashed a glass/window/mirror in anger- she said she was tired and asked Colin to take her home but as he's been drinking, Jeremy and Julie took her.
That´s right. Jeremy drove Sheila to the emergency unit at a hospital after she had rammed her hand through a window at her apartment. And correct, Colin was too intoxicated to drive her, so they (or he) asked Jeremy to do it.
Jeremy also drove Sheila home from that party because, again, Colin was too drunk to drive.
So two different occasions.
Sheila´s blood could well have still been in Jeremy´s car since the time he drove her to the hospital.