My 3 year old Buff Orpington is all of a sudden acting broody - she stays in the nexting box all day. I took her out yesterday and she ate and drank but went right back in the nesting box -- didn't sleep on her roost and was still in there this morning. I took her out again this morning and her combs which are usually bright red are turning purple on the very top - about 1/3 of the way down. I am going to isolate her and bring her in the screened porch to observe her more carefully. Any ideas? Old age? Heart failure? Egg bound? Thank you!