A few days ago, my cat started hissing at my husband for no reason. We have a spare bedroom that is "her room," and she just hissed at him when he walked by down the hallway. Ever since then, she has been hissing and growling at us non-stop. If we even try to go near her, she will hiss at us and then growl. The weird thing is, she will come up to us after a while and cuddle, then 10 minutes later is back to hissing. She has never hissed at me in her life, and now she is snarling and growling at me constantly for no reason. We have tried just ignoring her, we have tried spoiling her by giving her attention and treats, and we have tried spraying her with water when she hisses to discourage her from doing it (but that just makes it worse). The only changes I can think of are that my husband and I got slippers for Christmas and we have been wearing them around the hardwood floors, maybe she doesn't like the noise? My cat is almost 4 years old, and I adopted her when she was 4 months old so I am the only owner she has ever known. She is an indoor cat, she is spayed, she is eating and drinking normally, and there are no other pets in the house and no children either. Any ideas on why she is doing this or how can I stop this?