Cat Not Grooming Herself?

My cat has developed matts on her back despite her not being long haired and when I groomed her on three consecutive days she has a ton of dead hair and also what appears to be dandruff or dander (I am not sure which). Does anyone have ideas of possible reasons for this? I switched her from Nutro lite catfood to Hills Prescription diet food seven months ago upon instructions of my vet.
any ideas?

I don't like Science Diet. Unless there's are really good reason to be on a prescription diet food, you can just cut back on the amount you are giving of a better food and exercise the cat more.

If the cat was doing fine on the other food, switch her back and just give her scheduled meals and not free feed.

Comb her a few times a week to get the dead fur out. You might want to add some good coat supplement to her diet to prevent the drying of the coat. IMO its probably the diet food that is causing the dry coat.

Please check with the Vet. I am not saying you will have the same problem but I had a beautiful Persian cat that stopped grooming herself. She had Feline Leukemia.

Not grooming is a sign of illness in most cats. They simply don't have the energy.

However, I did know a cat once, a little orange DSH called Skimble, who was a bottle baby, not raised by a momcat. He didn't know how to lick himself clean; there was a female chocolate Lab who used to lick him clean as a kitten, and then when the Lab went to live with a family with a yard (as opposed to an apartment), Skimble had to have periodic baths whenever he started smelling 'catty' (NOT a good smell!).

I've also seen elderly, fat cats who simply don't have the mobility to clean themselves thoroughly. There was a 14 year old Persian mix in 10th Life Shelter when I volunteered there; she had to be periodically clipped because she was too old and too big to reach all of her fur; and it didn't help that she hated to be groomed. (I SO wanted to take her home.)

The vet put our cat on Science Diet W/D because she is overweight. However I have been thinking of switching her back to another food (any suggestions?). Also it has ocurred to me that she may have health problems and I am going to have her checked out.

Weight loss for kitty? High-protein food, portion control, and exercise....