He also may not be eating as much because he's also eating the other treats you're giving him, so postpone the treats for now - let him get used to his new home and form a routine.
Also be careful introducing him to all those treats so soon. New foods should be tried one at a time and a little at a time to make sure their tummies can handle it. It's likely his poop is runnier now than when you brought him home because he's overwhelmed by new foods. Stick to the food the breeder gave you, and if, later on, you decide you want to introduce him to new kibble do it by just adding a couple more pieces a day to his current food so he has a few weeks to adjust to it.
Keep observing him to make sure he is still eating every day, but let him stick with his kibble for now so you can see whether it's the other foods causing his poop to be like that, or something else.
Hedgie Mommy to little Piglet
* Abby *