Sinusitis and/or Mono?

I am 18. Went to the doctor on Wed. (Jan. 21, 2009): he diagnosed me with a sinus infection/sinusitis and wrote me a prescription for the generic of Omnicep (300 mg x2 daily). Talked with someone who had mononucleosis in their late teens/early twenties. We compared symptoms, and she believes I might have mono. Here are my symptoms: (present for about one week now)
-post-nasal drip (clear)
-headache
-my eyes hurt (maybe like "pressure" on them...)
-swollen lymph nodes/stiff neck
-dizziness
-fatigue (like you wouldn't believe)
No fever (98.2 F), blood pressure was fine (108/64 mmHg).
Maybe it is a sinus infection, maybe not. I have been on the antibiotics for approx. 36 hours as I type this. I know they take a little bit of time to work, but I have had several sinus infections (like 6-8 in the past 3/4 years), and this one feels different.
A penny for your thoughts.

[extremity]

I am a sinus sufferer myself, a lot of the prescriptions  don't rly help much, what has helped me was the over the counter saline. no meds or any other additives in it. use that 2 times a day.it helped me out, hopefully it'll help you. Take the advise of a doc though,that's what they work for.If you have doubts get a second opinion or third.

[kingash]

I was misdiagnosed for something other than mono for a few months before they caught it. Ask to get your white blood cell count taken if that what you believe it is. I was very sleepy all of the time and felt the eye/head pressure you mentioned. My gut feeling was set off by VERY swollen glands when I woke up randomly one morning. Get blood work done if your still questioning it!!!!