Optipro Anyone?

I got this protein to try from the health store because they guy there swears it is the best for WLS patients. Well I just got a small one thank goodness, because it makes me nauseas every time I drink it. I will finish the jug because I won't waste it. Has anyone else tried it and does it do that to you? It doesn't have any fat or sugar so that's not what is making me sick, I have no clue what is.