I have heard that it does cause gas. I've been taking it since the beginning of my take down, except when I take antibiotics, and do notice I have less gas but not take much. I personally like gas as it helps me clean out my pouch contents. Meaning I bend over when sitting on the throne after a BM for a bit and when I sit back up and have gas that "blows" the rest of the contents out.
How are you taking it? You can spread it out and take it a couple of times a day. I mix mine with Greek yogurt or in a fruit smoothie. Never with anything hot or when I'm going to eat anything hot.
If it is for sure making you nauseous then I don't know what to suggest other than to find something else to go along with what you were taking that may add more of the strains like are in VSL #3.
Sorry you are going through this. What works for some of us doesn't always work for everyone