Hi, in the 7-9 age bracket its amost certain that std,s are non exsistant in that age group so i would put these past incidents out of your mind. Symptoms of std,s are a white puss discharge coming out your penis and burning while urinating or genital sores that develop about a week after exposure.
Sexually transmited infections are predominalty in groups where sex is very active part of their life style. so just calm down.