Rice milk

So I’m lactose intolerant so I’ve decided to try rice milk as a substitute. It tastes pretty good, especially in cereal. I bought it Wednesday night and after I drank it I noticed I was gassy? Since I was gassy Wednesday night I decided not to drink any on Thursday but i was still gassy. I don’t know if it’s just the rice milk or if it’s something else but I’ve been feeling gassy and my gas does not smell good at all. It has been smelling pretty egg-like (which is disgusting I know) since the day I drank it

Could it be the rice milk or is it most likely something else and just a coincidence?

Btw I don’t get diarrhea or anything, just gas and small gas pains