I'm 5 weeks out with a dumb question.

It is possible to develop sensitivity to milk at this late date.  I made a shake out of some milk that was near it's expiration date and was nauseated all day.

It is possible! Either that or it could have been the milk itself. Give yourself a few days with no milk, then try again. If you have the same reaction, it could be an intolerance. At that point, I'd suggest some almond milk.