I really like garlic, I'll even chew up a clove raw occasionally. But good god man, 15-20 is wayyy too much, you can't eat that and be allowed in any social scene outside of north jersey.
When I was living in a tent on a beach in Alaska in the 90's (summer) I used to chew cloves of Garlic as an over the counter medicine. I think it worked like this. I would start chewing cloves of garlic, then I would stop. Then I would immediately start feeling better. It would've worked the same way with hitting myself over the head with a hammer, then stopping, but the garlic had fewer potentially severe long term side effects.