The nausea reflex action is probably due to an over worked CNS. Heavy squats, DL, new workout programs, , etc can do this because the system can be overstressed with doing too much in the way of a workout. The word OverTraining comes to mind. Sometimes the hands will shake and a dizzy feeling will go along with the nausea. Most of those post workout drinks (meals or whatever) were meant to be taken at least 1 hour after the workout. Letting the system calm down a bit and return to a normal range. Taking protein and/or carbs right after a hard workout does not insure that it will be completly digested and assumlated into the blood stream. You would be wasting the stuff and your money. What value would a "meal" right after a workout be if it's not being used by the body and passes right through. The toilet bowl will have the honor of receiving all that valueable protein, not your muscles. Or if you hurl right after drinking/eating one. Might want to wait at least a hour and than have a drink (rather than solid meal) that is sipped , not gulped , slowly. For me, a better option would be to have a steak dinner with a beer or glass of wine after a heavy, hard workout with-in a hour & a half. Good Luck.
