My advice would be to get plenty of rest when you're not feeling good, drink plenty of fluids and eat really well to build your strength up.

As for getting back into exercise, try working your way up from stationary bike and see how it goes. Listen to your body and then slowly increase the load.

It's important not to just sit around resting all the time. Your body will just become more unfit and prone to a longer recovery. I buy into the work the Uni of Buffalo are engaged in, bringing athletes back to fitness by allowing the body to become accustomed to regulating itself with exercise.

When you progress from there, try to work in light running and if all goes well, light drills. Make sure to get plenty of air and water while doing this and know the limits before over exerting.