I just learned the other day that I've had a sinus infection for around 3 months. So I just started taking antibiotics. I failed to mention though that my neck has been hurting, and I've been having vision problems. Should I just look past this or go back and tell them? I read that this could be a sign of the infection spreading to the brain but I'm worried that I just might be paranoid.

What does it take? A phone call? Do it.

What antibiotic are you taking?

I often wonder why people ignore physical symptoms for so long. You really need to tell your doctor about the neck symptoms and SOON!
If a bacterial infection does work it's way into your brain, the effects could be fatal. CALL THE DOCTOR!