I took Flexeril for a couple of days for muscle spasms in my neck...

I took Flexeril for a couple of days for muscle spasms in my neck and shoulder area. It was very effective at first. Then one day I went to stand up and my knees went week and I couldn't stand for a couple of moments. After 10 minutes I was fine, I called my doctor and he told me to stop taking it. I went for physical therapy and that worked very well. This was 10 years ago but I still remember the name of the drug. I don't know what caused that one reaction.