I have chicks being brooded in the house since their hen rejected them. The weather was hot enough to put them out in the grass under the wire top of a hamster cage (with a brick on top of course) so they can scratch in the dirt for a few hours. The last few days have been raining, so they've been inside. Since last night, two have become constipated. and this morning have messy bums. What is safe for constipation at this age? It's still raining, so no outside.