I have had a fever and headache for 3 days. 1 week ago i came in intimate contact with someone who now has mono. can i contract mono that fast?

4-6 weeks: The incubation for mono is 4-6 weeks. The outstanding feature is sore throat. I suspect you have something else.

Too soon for mono: Much too soon; the incubation period for mono is typically 4-6 weeks. But if you have had other intimate exposures in past 1-2 mo. with the person with mono (sex, kissing), you might have caught it from from him or her a few weeks ago. You could even be the source of that person's infection. See a doctor if your symptoms don't clear in 2-3 days or if other symptoms (sore throat, swollen glands).