corner of mouth edge of lip cutwound not healing

hi, ive had this problem for a week. i think i had a pimple or something at the corner of my mouth (just where the lips begin) and i think it went bad because i might have popped it or because of the skin stretching when i opened my mouth. so its not a pimple now and the skin at the corner of my lip has gone bad and looks like a weird cut. its not healing and even if it is, it is interrupted whenever i open my mouth. and when i open my mouth like really wide, then it can sometimes bleed. here are the images of what it looks like. please help me.
thanks in advance.
//www.curezone.org/ig/i.asp?i=69870
//www.curezone.org/ig/i.asp?i=69871
//www.curezone.org/ig/i.asp?i=69872 Tweet