The ephedrine/caffeine stack has always been my favorite combo as a thermogenic. However, as much as I love it and think that it is great, my suggestion to you is simply to stop taking it if it causes too many problems.
There are a ton of very effective fat burning combos out there to try and cycle with, don't let this be a route that makes you miserable. Really, if it makes you feel bad, just don't take it at all.
You can fool around with dosages and see if that helps, but if you need or have to quit, then just do it and find another alternative.
Good luck bro!
BMJ