Thank you for writing!
Did you have sex ed at school? If not, it's a good idea to study on your own so you know how sex and the human body works. You can read books on this or search our own site. This will eliminate a lot of stress than the unknown can cause.
A woman cannot get pregnant unless she has unprotected sex (naked) with ejaculation. She would also have to be ovulating or be within five days of ovulation. Sperm will not travel through a layer of clothing to impregnate.
So a pregnancy cannot occur from what you did.
Your period isn't due until today so try to relax.
About the itching and discharge - antibiotics are know to cause yeast infections. This may be what's going on - see your doctor.