I never get sick. Ever. I haven't been to a doctor for sickness in 15+ years. We had a real rough year with job struggles and finally things got back on track this past fall. We didn't know what to get DS (4 at the time) for Xmas so we decided to take a long weekend trip to Disney. We normally go 2X a year, but with the job issues it was going to be about 15 months between trips.
Well, at lunch the day we were leaving I started to feel a bit achey. We had an evening flight and I was leaving straight from work. It got progressively worse on the trip to the airport and my throat was on fire. My whole body ached, I had a fever, so uncomfortable etc. I struggled through two days at Disney with plenty of rest, sore throat losenges, etc and still felt HORRIBLE. I was so hesitant to waste precious park time because of the short trip and my son was so looking forward to being there. But on Our 3rd morning I went to a CVS Minute Clinic near WDW and was diagnosed with Strep and started on the antibiotic right away. I felt so much better that evening and almost perfect the next day (which was also our last).
I still had a good time even being so sick, but the antibiotics kicked in so fast! Definitely give it a day or two to work before you worry too much!