feel bad

Short definition from Wiktionary

Verb

1. 1
   To not feel good; to experience an unpleasant physical sensation.
2. 2
   To not feel good; to experience an unpleasant physical sensation: To feel ill or sick.
3. 3
   To feel remorse or shame for one's actions.
4. 4
   To feel pity for, to empathize with.

Adjective

1. 1
   Creating a feeling of anxiety or despair.