If you're taking mestinon every 6 hours and you choked at 4 hours, this could definitely be the problem (based on my experience). I have to take it every 4 hours (and sometimes every 2 hours if my symptoms are real bad), so it would make sense to me if you have problems at the 4 hour mark.

I do use the Timespan at night so I don't have to wake up during the night to take meds. You probably need to check with your doctor on that.

Good luck.