Anorexic Mew

Mew hasn't been eating well lately. I have a feeling she stopped eating altogether the past couple of days. She's been very inactive. She'd only hide in my room and sleep. I fed her with some milk last night and she drank quite a bit of it. I was relieved she would at least take in something nutritious. I hope all that milk wouldn't cause her diarrhea. There's been three instances when I caught Mew hissing for no apparent reason and ran away from her sleeping spot. I have no idea what caused her action. This morning, I couldn't find her around our home. I don't know where she was hiding. I checked her usual sleeping spots and she wasn't there. Mom also didn't see her this morning. I hope Mew isn't sick... :(