I have had Isopure and I have never had any problems with jitters. That sounds really strange I don't think it has any sugar in it either so that wouldn't be doing it either. I am at a loss at what...
I would get your self in to a routine if I was you. That way you are less likely to miss a dose. I take mine pre work out and then about 8 hours later.
Add some whey protien to your stack and you should be good with it. I don't think you have to worry about adding that much mass but the protien bars might do a little bit since they probally have...