Am 25yrs of age and after several sexual activities with my girllfriend, I noticed some red dots on the head of my penis.can someone help .thxs

It sounds like you came into contact with vaginal yeast during your sexual activities. It's fairly common and nothing to be disgusted with, it can happen if neither one of you are aware that she has a yeast infection at the time of activity. If the spots go away after a couple of days and are in no way whatsoever uncomfortable this is likely the case.

However, if these bumps are raised at all, or are irritated or cause discomfort it could be something more serious like an STD.

Don't hesitate to go to the doctor about this issue. It's important to seek professional medical advice from your doctor when you have questions about a sudden change in your body. Hopefully knowing the options a bit better will help you to not stress as much over it, but it's only advice and not in any way a substitute for your doctor.