Severe flea bite allergy

[Cantbelievethisishappening]

Just after some advice
My outdoors 10 year old cat has had a flea bite allergy for a while now. This was confirmed by a vet a while back. I am always treating her for fleas but it seems to be getting worse. She is constantly licking and chewing and scratching herself to the point of having bald sore patches on her. She also has lots of small scabs on her body. I have brought her in tonight and her shocked at how she looks. Over the last couple of days she has chewed/licked a huge amount of hair from her side down to the skin and it is sore and in some parts bleeding. Am now wondering if it could be something else.

I have phoned the vet and will be taking her tomorrow but am wondering what they can do for her. She has also been losing weight. She looks dreadful. I am sure the vet will think I am useless as an owner.

Any thoughts/input would be gratefully received