This metronidazole is a dreadful antibiotic. Hurts my gut. But will that get rid of infections?

Depends on… What infection is being treated. If your doc prescribed it for a specific infection, it should work unless the infection is caused by a germ that is resistant. In such cases, the doc will culture the infection (if possible) to find out what abx works best. Avoid any alcohol (even mouthwash) with Metronidazole & use sunblock if going to be outdoors more than few minutes.