A. The most concerning part of your message is the "hiding in unusual places" . There are 3 things cats that are truly sick do: stop eating, stop grooming and hide. Being that she also is lethargic and has a change in stool, I suggest a visit to the veterinarian as soon as possible for an examination and probably some bloodwork. It is difficult for me to give you an idea of what is going on since her clinical signs are vague and can be related to a multitude of reasons.
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