Will a small amount of junk food wreck my ability to run faster?

I haven't gone to track practice for my highschool in 2 days, since i can't really run when I'm sick and have a sore throat, but I'm going tomorrow. I was just wondering if a small amount of junk food will make me slower, because I eat SUPER HEALTHY everyday with no junk food, but today at lunch I had a tapioca drink (only drank half), then after school I had 2 small white fudge cookies, and a brownie. Now I'm feeling kind of sick...maybe its because i'm not used to eating all these sweets in one time, bit idk..