Well, unless you have a race coming up, "losing form" for a week or two wont actually kill you. As soon as you get healed and start biking again, you'll be back in your original shape after like two weeks.

Seriously, take it easy and let your body heal and fight off the infection. Ride for fun / as much as you can in the meantime, not to push your already weakened system; if anything you may be shooting yourself in the foot.