Well I recently had a illness, and I figure it would be easy enough to fake...
So I will tell you what to do and you can get out of school for a full week and it looks real.
First of all, what is your mom like?
MOM A: Takes you to the doctor after two days of being sick
MOM B: Doesn't ever take you to doctor
MOM C: Is untrustworthy of you, will probably take to doctor.
This will only work with mom B
Pre planing is important Stash food in your room.
Day 1. Saturday, act a little sick, act tired, don't go out long.
Day 2. Sunday, Complain of stomach being sick, take a nap or two and lay around all day.
Day 3. Monday, Wake up at 1-2 am, (if you have gone to sleep) Tell your mom you threw up... Don't go to school, sleep/play computer...
Day 4. Tuesday, Keep throwing up. Eat some stashed food but dont eat anything your parents know about.
Day 5. Wednesday, Complain of stomach pains around the belly button. Then say they moved to below your right ribcage. Get your mom to google it, she will probably find out that it could be apendicitis (spelling???) Say you cant sleep because of pain and you want to go to emergency room because you appendix could explode.
Tell doctor that you had pains around your belly button, they moved to below your right ribcage. Say on pain scale its about a 5-6. When he starts to question you more, tell him the pain did not start till after (Important) the puking stopped. They will probably give you a IV, do X-Rays, and take blood. They probably will decide that your Colin swelled up due to a stomach virus, and it should be better within 24-48 hours.
Thursday&Friday, Start getting better, and you should act fully recovered by Friday afternoon (1pm or so).
Don't go to doctor, because they will look at your throat and see that there isn't any inflammation (from puking)
Have fun with your week off from school!