7 hrs after fainting and vomiting, fever blisters appered on my chin. Can this still be related to my episode? Or herpes? And is this contagious?

Stress. "fever blisters" are caused by herpes simplex and are contagious. We are all exposed to herpes simplex at a young age. Some people continue to have outbreaks during stressful times and with exposure to the sun. Others may never have repeated outbreaks. Your body was stressed due to the vomiting and fainting episode you had. Thus, the outbreak of herpes simplex. Valtrex will treat this.