50 is above the max recomended dose for remeron, did you mean 5? this would be a low starting dose
all antidepressants can cause early side effects including dizzyness, try to put up with it as it probably will stop soon as you get used to the med
if you stop rthe remeron now, there wont be many problems as you havent been on it or the other antidepressants long, the lorazepam will help