Check their water.

While Ginevive gave you some great suggestions this is one that often gets missed.

Every now and then water bottles get stuck closed and the animals are unable to get water ... they exhibit the same signs that you stated.

From my own experience I've noticed that this only happens to my mice when a drinking bottle or valve gets stuck closed.

I fill water bottles all on the same day leaving about an inch of air in the bottle to create less vacuum, I can then tell at a glance if one enclosure is consuming less water.

Bryan