When you had the issues with dairy, did you just do dairy for one day and then go back to Whole30 right after? Did you continue reintroducing other things, even with the persistent digestive issues? Sometimes, if you have a really bad reaction, it can take awhile for your system to get it all out and reset itself. Many people do find they have issues with dairy after being on Whole30. I wasn't nearly as bad as what you describe, but dairy now makes my stomach uneasy, full-feeling, nauseous, etc. I've narrowed it down to cheese moreso than other dairy, but I'm basically avoiding dairy altogether now.
I would think it might be worthwhile to go back to Whole30 compliance until ALL symptoms are gone. Then give dairy one more try. If it affects you like this again, you probably have your culprit. Then, go back to Whole30 completely again until all symptoms are gone before reintroducing anything else. Sounds like you would benefit from doing the "slow roll" reintro instead of the "fast track".