I recently ran out of protein powder and grabbed a different type from the local store. After about a week my arms started getting sore as well as the joints and it wouldn't go away. I stopped working out for about 10 days but no improvement.
The stuff I usually get has creatine and glutamine in it but this new stuff had neither. I had been adding creatine to the shakes but not glutamine. I started adding glutamine and bam 2 days later my arms are better and I'm back at the gym. Has this happened to anybody else? Was it just a fluke or does glutmine have withdrawal symptoms?