Rabbit scratches herself till she bleeds and pulls out her fur

I have a dutch dwarf lop called tulip. She is going to be 3 soon, and she has always been a healthy happy bunny.
Last year she got a few bald patches on her back and had chewed the skin so had scabs. I helped keep the area clean and it healed and the fur grew back. I asked the vet at her checkup and he thought she properly had a insect bite or something that bothered her to chew on it.
Then in January I spotted another little bald patch, but it was already starting to grow back so I left it, and this evening I just found two patches on her back where she has chewed or scratched herself so hard the skin is red raw and bleeding slightly. She hasn't pulled out any fur yet, but I think this will be the start of a bald patch.
I don't know what to do, I never actually see her chewing or scratching in that area to try and stop it, I have not changed any of her bedding products and have been trying to find out what could be causing this.
Is this normal for a rabbit?

On a side note my rabbit is super clean freak, she cleans for hours every day and cleans her ears a lot, around the edges of her ears the fur is very thin or gone from the amount of cleaning she does, the vet said it was not a problem though.

If I were you I'd take some photos so people on here might be able to give you a better idea of what it is. Other than that she needs to go to a vet as soon as possible really, before it gets any worse.
If your vet can't offer any real advice I'd seriously consider changing vet.

I'm afraid I wouldn't be happy with what your vet has said and would change to a rabbit-savvy vet. If you don't know of one, you could start a thread 'Rabbit-savvy vet wanted in .................'
By the way, is your rabbit neutered? What are you using for bedding?

Well I am with the most savvy rabbit vet in the area, I did a lot of research when looking for one to neuter her. They do special rabbit clinic days each month were you can take your bunny for a check up, and shots etc, but I just missed this months and to go outside of these clinic days is expensive as a student.

Bedding wise she has lots of hay in her cage as she likes to lie on it, and then I keep a higher quality hay in a rack for her to eat. She has a toilet box in her cage with wooden cat litter pellets.

I just remembered I clipped her nails last friday, I do file down the edges a little afterwards, but might they still be too sharp?

Here is a picture of the new patch.