Is this diagnosed? or are you saying you have a sick hen? I'm guessing sick hen.
If going to a vet is not an option. Maybe the best you can do is supportive care. Keep the hen warm, in dim light to decrease laying. Offer treats or anything if she is not eating. You can get vitamins and/or anti-biotics at most feed stores.
I have found that by the time I realize I have a sick chicken, it is very sick. So I throw anything at it, that I think might help.
I agree porkchop. Unless the bird is a valuable breeder or rare [expensive to replace] or a pet, it can be VERY expensive to treat a sick bird. This goes even if it isn't a chicken.
What are the symptoms? One of the best treatments you can give is Tylan. If you are in the US, you have access to Baytril, you can use that. Both Tylan and Baytril you will have to gauge the dosage to make sure the medicine works correctly. As a rule, I treat for 3 days and if I see the bird respond, continue to treat for 5 days.
Any bird you suspect of having a CRD, you should immediately remove from your flock and quaratine. Keep it warm not hot. Watch the rest of your flock to make sure no one else becomes ill. If they do, you may have to cull your flock as you likely may have a infectious CRD.