Stomach Issues?

Anyone else have stomach issues when on the road? It seems like the first few days of a trip I either feel nauseous when I wake up or things aren’t right “down below” (if you get my drift). It seems to settle as I near the last few days of the trip. So I don’t know if it’s just nerves or if I need to take probiotics to get the digestive track in better shape, etc. I’m a 41 year old male. Any suggestions would be appreciated. Thanks!