I cannot believe this medicine is still being given!! I am taking...

I cannot believe this medicine is still being given!! I am taking it for an infection. This is my 5th day on this medication because after extreme nausea, stomach pain,diarrhea, metallic taste in my mouth, and a mild headache, I was told by the doctor's office that I should finish this medication, and that it would get better. I don't know why I listened, I will be stopping today. I actually did get better for about 2 days and now all the symptoms are back with a vengeance. I felt very sick last night after I took it and this morning even worse with extreme nausea and dry heaving. I never cry and I cant stop crying now-for no reason at all I am extremely emotional. I would much rather be naturally sick like I was before than feel like this, I am a wreck.