Dear XXXXXXX,
First, let's discuss the symptom that obviously concerns you the most - the purple spot. My rule of thumb for new skin lesions is to observe them for a few weeks and have your primary care physician or a dermatologist evaluate it if it does not go away. Having said that, in your particular case, it is possible that the blister which arose was a cold sore caused by herpes virus (before you freak out - herpes virus in and around the mouth are extremely common and not a sexually transmitted disease. Herpes viruses live dormant in many of us and surface in response to certain stresses such as colds and sun exposure), Alternatively, the blister could have formed simply from sunburn. Regardless of which, the purple spot could be a little collection of blood from a vessel weakened by the blister. Blood in the skin goes away very slowly (have you ever noticed how long it takes a bruise to go away?).
So you might wish to wait 2-3 weeks after the sun exposure and if the spot is not going away, then have it looked at by a qualified physician.
Regards,
Dr. Schwartz
Doctor
Over 45,000 patient visits in 13 years private practice.