Help with non-stop scratching bald patches on her head...

Hi,
I have a 3 year old cat who when we rescued her at Christmas, had 2 slight bald patches on her sides of her head.. which were not very noticeable at first.
However, about 3 months ago she started aggressively scratching them that they began to bleed. She also got into a bad fight with a neighbours cat and this lead to one of the scabs to become a much bigger scratch. Took her to the vets, they gave us an E-Collar which she has had on for about a month now and although it heals, the second its off she scratches at it madly.. as she would because a big scab would become itchy when its healing..
I actually think she has eczema, and I just wondered what any ones thoughts or advice would be? It seems as though if we were to keep the E-Collar on.. once it heals she just scratches it all over again.. and the E-Collar seems to be causing her a lot of distress when it doesn't seem like it will work in the long run.
If anyone has any advice at all please post a reply,
Thanks,
Cleo

First I'd cut her hind nails so she can't hurt herself.

Then I'd take her back to the vet and have her skin checked. It sure sounds like a skin condition of some kind to me.

I totally agree, something is causing her a great deal of discomfort and that underlying issue needs to be found and dealt with for her to stop scratching after the wounds/scratches have healed. A vet visit is in order, imo.