In need of possible diagnosis. Possible STD?

hi, I am going to assume u r very young so if I am wrong please let me know
now as to your symptoms; could easily be YEAST
now as to getting a 5.5 PH level, that seems to scream that u r out of wack with normal
NOW HERE IS WHY; your body is a neutral 7 ph which u can see if u look on a bottle of baby shampoo because it is designed to have a neutral PH so as not to sting the little baby eyes.
BUT HERE IS THE DEAL; your vagina is actually supposed to be around 4 PH, (little lower or little higher BUT NOT BY MORE THAN ABOUT 4/10ths)
NOW HERE IS YOUR HOMEWORK ; look up symptoms of yeast infection
and then look up symptoms of vaginosis (bacterial as opposed to FUNGAL in yeast)
try not to worry too much in between and if I am right and u r young, talk to mom because this is common and she has been there many times and ACTUALLY wants to help and care for u (i am assuming)
i hope this was of help and not confusing