I agree with giving his stomach a chance to calm down. When we adopted Toby they told me to expect runny poops for the first week or two as he adjusted to living in a home (we got him straight from a GPA Kennel at a dog track). However, the 2 weeks came and went, still his poops were mushy/runny. I had to try a variety of foods before I found one that worked for him. I tried Nutro, Pro Pac, Pro Pac Holistic, and Biljac with no luck. Finally I tried Science Diet Sensitive Stomach. Not only did that firm up the poops, it completely eliminated the gas. And Toby is able to handle treats now with no digestive problems, either.
So my advice would be to give him some time to get used to his new surroundings, and then go from there.
And Congratulations on Dutch!!!