Pet Rat Help? (Five weeks old)?

So I adopted a male pet rat from the local animal shelter yesterday. They had the rats separated by sex like usual and there were only two males. I got one and named it Oreo then I went back this morning and got the other and named it Snickers. They are in the Harts play city cage right now I know I need to get a bigger cage soon. I was looking for treats for them and I found yogurt bites. I read that they like yogurt but on the bag it says for rabbits and genie pigs, can they still eat it? Also they have a tunnel to sleep in and nesting fluff along with water and two small bowls of food. They also have wood chips that are unscented and all natural. I also got them a piece of wood that’s shaped like a wedge of cheese for them to chew on along with a small wood log for them to chew. They seem to be getting along fine. I noticed yesterday at the shelter Snickers was fine but on the way home he sneezed a few times and his poop is light brown and not black. Is he ok? Could it just be from being separated form his brother for a day? Any help would be greatly appreciated im worried about him. He doesn't have any discharge or anything and his eyes and skin are still clear. He also is still very active and lets me hold him just like the other. Should I be worried? They also have pretzel log treats. What else should I get them for treats and food. They have a wheel that's attached to the cage that they like to lay in along with their log. They also have a small wood ladder along with a toy that hangs from the ceiling with wood blocks and a bell on the end. Any other toy suggestions. Thanks in advance. :)