E.R.
This happened with my younger son! Not only was dairy a source of nastiness, but also anything remotely acidic, even ketchup! I just really tried to be creative in obtaining the protein and calcium I needed by eating more nuts, fish, etc. Also, Tums is a great source of calcium. I noticed that once my little guy was not exclusively nursing, the problem tended to ease up a bit, though at 2.5, he is still sensitive at times to certain foods. Best of luck!