Metronidazole and nausea

I started taking the Metronidazole (prescribed 1 tablet, 2x/day) 500 mg. After three days, I experienced fatigue, headaches, which got worse. By Friday, I had to leave work, and I was in bed w/flu-like symptoms: my head felt like it was to blow off, nausea, and hollow back pain in lower. I had to stop taking the meds. All symptoms subsided within one day, except my back hurts when I walk, and the headaches are infrequent but still remain. I called to report to my doctor. The nurse said that she had not heard of anyone having side effects from the drug.

I have been taking Metronidazole for 10 days 500mg 3 times a day for a bacteria in my colon and in all honesty i have the metallic taste in my mouth , nausea , headaches , and cannot get erect.. I think it has affected me sexually because i am taking so much of it..This is the worst medication i have ever been on.