Do I have Oral Thrush?

I'm 16 years old. I had my wisdom teeth removed last Tuesday. I have been taking Penicillin everyday since 3 to 4 times a day 500 mg tablets. Wednesday i woke up barely with a sore throat. Each day it has gotten worse. Today it has been unbearable. My dentist said he's sure it's a cold. If I am allergic to the penicillin he said I would breakout on my skin. It's not sinus infection as It's my entire throat. It can't be a cold in my opinion because I would have more symptoms. I had a stuffy nose earlier but still. I DIDN'T GET ANY SLEEP LAST NIGHT DUE TO MY SORE THROAT! I took two penicillins today as at Patient First I told them my dentist said it's probably just a cold. So they didn't test me for any allergies to penicillin. I come home still sore throat worse than ever. I read about yeast infections and oral thrush...Could I have oral thrush? I have a horrible white dot with blood around it on the roof of my mouth. And a lot of the back of my throat is white.