Anyone else get a clenched jaw with Ritalin IR? I also get jittery on the "come down."

I was on Concerta before, and didn't feel any side effects except for some dry mouth and occasional drowsiness (just when upping the dose). I'm not sure why I was not getting this side effect with Concerta, when I am with Ritalin IR, since they are essentially the same, just difference in release. I have taken this amount of Concerta with no problem...any ideas?

In all other ways, I feel the amount of medicine is good. I am so much more focused and less impulsive and hyperactive. :p

I plan to ask my Dr. about going back to Concerta. I'm just trying to figure out what to do in the meantime. I don't like the 3xper day, but can live with that, I just really don't like the clenched jaw and jitterineess, especially since it is every three hours.:(