I'm not good 和 I'm not well

I'm not feeling well I'm not so good I'm not feeling good I'm feeling not good. i m not good at I'm not feeling ____ (good/well).I'm going to see a doctor. I'm not feeling well u--- now I'm not feeling well today. I'm not (feel) well now I'm not feeling well.为什么用well而不用good I'm not good at guess. 怎么回答i'm not so good