Pictures Of A Throat Infection I Have A Sexual Question?

I have a sexual question? - pictures of a throat infection

I had sex with my boyfriend on Sunday. I gave him oral sex, and now, on Wednesday, I have a sore throat. Yesterday I noticed. I used a flashlight to the back of the neck, check, and there is a grain like bump on the back of the neck. I saw pictures of a throat infection on Google Images and this is exactly what it seems. Not using condoms during oral sex. Also said my friend, he tested for sexually transmitted diseases and they were all negative. Should I worry, it's something worse than a sore throat?