You should try to change the food and see if the color change was because of the food, also if you have red/orange colored food, if they are that color because of dyes I would not use that food. Dyes are not good in hamster food, I recommend using the Higgins Sunburst food and mix it with the Missouri rat and mouse pellets. That would be the PERFECT food, the rat/mouse pellets would just add more protien because the Sunburst just needs a little more, that would be the best pet store food, other pet store foods are not very good for hamsters actually.. I hope you figure out your problem, and I hope you and your hamster have a wonderful day!