pregnancy lactose intolerance?!

So every now and then I get these terrible stomach cramps and have BAD diarrhea, sometimes for hours 😳 Sorry, I know that's totally gross. Anyway, I've figured out that it usually happens after I've eaten a large amount of dairy--milkshakes, ice cream, etc. I'm not lactose intolerant and have never had a problem with milk so I don't know why this is happening. Anyone else had similar experiences??