Yeah, I think you'll have to stay off of dairy. My dairy-intolertant daughter turned one last month, so we tried introducing dairy to her diet in the form of a half a grilled cheese at lunch. It took a week for her symptoms to come back, but -- and here's the worst part -- almost 2 full weeks for them to stop.
However, when I was still nursing I found that I was able to re-introduce hidden dairy (i.e., things made with dairy that had been cooked, processed, or baked) in small amounts without it bothering my DD. If you do that, I would advise keeping a food journal because it can be really hard to figure out what is affecting your kid --especially if they don't have symptoms right away. Best of luck!