I would suggest getting new tylenol, lol. I can't say for sure how it's going to effect you being 7 years old, but it's definitely less effective.
I use stuff that's old, but if it's over 5 years I throw it out. I'd rather get something new and be sure it's doing what it's supposed to be doing.
Vitamin C, fruit smoothies, real vegetables, and (if it's an option) going to the gym and sweating it out. And rest. That's typically what I do when I get sick.