Took the perscription (500 mg, 2X daily) for three days before I ...

Took the perscription (500 mg, 2X daily) for three days before I started having bad side effects, then it hit me like a ton of bricks, and I quit immediately. My digestion has been real messed up, my stomach and intestines have felt as though they had a meat grinder turned on inside. My head has felt as though the top of it was going to come off. I've been off the pills for 3 days now and my head is beginning to feel better. My major complaint now is that my legs ache. My thighs mostly, but also my calves some. I had no idea I would get so sick from an antibiotic.