Hey bblair,
Heavy metal contamination of protein powders was in the news recently, so if you are doing this for health you should give that some thought. The best resource I found was the
Clean Label Project: https://cleanlabelproject.org/protei...20Certified%3A There is some data from Consumer Reports also available, but the CLP was more comprehensive and free.
On my vegetarian diet I usually need two scoops daily of protein powder to meet my protein goals. Plus my nutty home made granola for breakfast with 25g (but 800 calories). Lots of pulses for other meals and sometimes yoghurt rounds out the total. Occasionally I stray from my veg diet and eat a dead animal.
I have tried a bunch of protein powders but can't comment on any stomach problems - that's not my issue fortunately. Must have been all that dirt I ate as a kid.