I was prescribed 750 mg per day yesterday for 5 days for bronchit...

I was prescribed 750 mg per day yesterday for 5 days for bronchitis. I took my second pill today and I cannot bare weight on my legs, the achiness and knee pain is excruciating. My husband called my brother-in-law to help get me to the car so we could go to the emergency room. While we were waiting for him, I looked at my prescription info because that was the only thing different. I am also allergic to sulfa drugs and thought it could be a reaction to the meds. I called the pharmacist and was told this was not a common side effect but definitely could be from the drug and to stop taking it. We didn't go to the er but decided to wait and see if this would become better. I can't walk and I'm 42 years old! After 2 pills!!!