If I try to get my cat on her back she kinda growls at first, but if I try it twice she will get mean. If I pet very lightly she might let it slide once or twice. I'm just worried she's in some kind of pain. Does anyone know about this?
The lower back is often a no go zone when petting a cat.
This is the area a male cat grabs hold on in female cats while mating, and it can be damaged by the males claws. It often does get infected by this.
When cats fight, they do try to protect their head and belly area, but they are not able to protect the lower back, so this area will often get hurt and infected in a fight.
You should check the lower back of your cat at regular intervals. Often the fur in this area can feel a little hard or like it is clumping together if there is some damage there. Sores in this area are almost never deep, but they can get infected.
My female cat is spayed. She is an indoor/outdoor cat, but she still gets hurt in the lower back from time to time by the overeager male cats.
So your cat's reaction to being petted there is about the same with or without any pain. Many cats simply do not like to be petted there.
It could also be that this is a submissive position. I have a neutered male cat who is almost five and hates being rolled over. If you notice when cats or (dogs) have a "disagreement" the winner is the one who doesn't roll over. It could be that your cat is seeing this as an attempt by you to dominate her, and she's just not having it.
It is possible the cat has some sort of pain in its back that is exacerbated when it is petted in that area, and so you may want to take it to a vet to have it checked. One possible relatively common cause of pain like that is arthritis.
But it is also pretty common for cats to just not like being petted on their backs, especially their lower backs. For many cats it seems like petting can quickly become too much for them. Long strokes all the way down their back seem to be too much for them really quickly. The gentlest way to pet a cat is to stick to areas around the head and neck.
Sometimes (but by no means always) this may be related to a relatively common disorder in cats called hyperesthesia, which seems like it might feel to the cat like its skin is being irritated or like a sudden sting or itch. The normal symptoms are twitching of the skin along its back, sudden frantic grooming or scratching, sometimes to the point of pulling out hair, thumping their hide legs on the floor, violently swishing its tail, or even jumping up and running as if it were stung.