hi, med student here, if you cannot get it to stay unretracted i’d recommend going to A&E/ the ED, another issue it could be though is if it’s not lubricated, and you have very slight phimosis, it can stay behind the head, i’d recommend getting your pen15 really lubricated, try to get some under the foreskin, and when pulling your foreskin over, pull it a bit as this can help it become unstuck and could save you another embarrassing hospital trip; hope this helps