Is your cat super friendly when she sticks her rear end up in the air? I adopted a feral cat. Didn't know anything about her until she cried like that and stuck her rear in the air. My cat did this also when she was in heat. I called my vet and they let me know that she would do this every few weeks if she was not spayed. She is spayed now!
Why Is My Cat's Butt Sticking Out Like Cone And Her Back Like Dented In? I Am Really Worried.. She Just Has A Constant Meow Cry.
Your cat probably has plugged anal sacs. There is a tiny gland at about 5 and 7 o'clock on the wrinkled area surrounding the butt hole. Beneath each gland is a tiny sac. The glands secrete a drop or 2 of really smelly, oily stuff each day. Theoretically, the sacs get squeezed and emptied when the cat poops. Unfortunately, commercial cat food has insufficient fiber to make that happen in our modern world. You can manually express the stinky stuff or go to the vet - if you go, watch carefully so you can do it at home for free next time. If the sacs get plugged, it's painful for the cat.
Is this cat spayed? It sounds like she might be in heat. How old is the cat?