My 7 year old gets small patches of petechiae that come and go for about 8 months now. should i be worried?

Petechiae not normal: Petechiae are not normal and are caused by low platelets or fragile vessels and if ill, infection, and CBC is a basic test. That said, it is not uncommon for someone to get petechiae on the face from coughing hard, straining or vomiting. It can also be seen from vigorous scratching, something that causes localized suction or a tourniquet-type wrap, and would not need further assessment.

See Dr: Probably not petechiae. If they really are, then it should be diagnosed promptly.