Why does hemp milk upset my stomach?

I went vegan a couple of months ago. Although it took a few days for me to get used to soy milk, I now love it. I recently tried rice milk and almond milk and love them both. I now drink only almond milk. However, a few days ago, I started hearing about hemp milk (or hemp seed milk.) I did some searching on a few different websites and decided to try it. Last night, I poured myself a small gl (maybe 4oz) to try it. It tastes pretty good. It has a very nutty, earthy flavor. About 10 minutes later, I started feeling pretty sick. I didn't attribute it to the hemp milk, but after having another gl tonight, the same thing happened. Is there something that could be giving me an upset stomach? The only thing I can thing of is the thickening agent, carrageenan. I don't think I've had problems with it in the past though... Any ideas?