I recently managed to rid my ex-girlfriend of the flu (or whatever it was) by stopping by my local health food store and getting a bottle of vitamin D-3 (think it cost about $7.00). Can't recall exactly what the IU count was, but I think it was about 1500, so she only needed to take two pills each day.
Two days later, she was 100% better!
If you have a VitaMix or equivalent (no, I don't mean the Magic Bullet), you could make a smoothie out of fruits and veggies high in vitamin C.
Don't worry about the taste; the fruits will outshine the veggies.