It hapenned to me too during my only X2 Recovery Week.
The best thing to do is let your body heal completely. Drink lots of Vitamin C juices and stuff, then comeback strong after the cold is gone.
I like the "punch your sickness in the face with exercise" approach but it is likely less popular/wise.
Lots of chicken breasts, tuna, other fishes, and the occasional steak/extra lean ground beef. I order bulk whey protein ($175 for 25lbs) and have usually 2 shakes a day in between meals.
Only whole wheat breads, and limited at that. Most of my carbs came from the veggies I ate.
The supplements I used, other than the whey were really just for general health.
I take NOW ADAM multivitamins (they're cheap and they use the better versions of certain ingredients)
Vitamin D3
Omega 3
GCM (glucosamine) for joints. Not sure if it actually works, so I may stop that one.
I tried creatine but didn't notice anything really and I felt a little off, so I stopped.
I didn't really have many weights at home, only 10, 15, 20, 25s so that's the max/min I could use for any given exercise. Sometimes it's definitely not enough, especially for things like lawnmowers. It won't be enough soon, for curls, but for now it's manageable.
You're now like a text book case of P90X success; you used a smart diet, you didn't use any crazy supplements, and you just plain worked hard and kept on the diet with amazing results to show for it. Awesome stuff man.