That's horrible when the IBS makes you feel like you're going to pass out. I've only had that a few times (and not for a while now), but it's really scary. Hope you feel better now.
I am supposed to be doing a short bus (3 stops) journey to the shops a few times a week as part of my CBT but haven't managed it. I did it a couple of times 3 weeks ago and felt horrible and haven't plucked up the courage since. Really wish I could ignore the feelings.
I know what you mean about being scared you'll panic with your son. I'm the same. William is over 3 now and I still take him in the buggy because it gives me something to hold on to when I feel wobbly. It's not fair on him, and I feel guilty. Bloody hard, isn't it?