Cat Self Harming - Please help

I have a 7 year old neutered silver tabby tom cat. At about the age of three he started scratching his neck near his face, when taken to the vets they thought this was because he had an abcess that had started to heal. He was given antibiotics and steriods but he wouldn't stop scratching. Over time he started to scratch both sides of his face. We bought him a cone collar to stop him getting to the area and left to fully heald and all the fur had grown back before removing unless supervised to allow grooming. Once the collar was removed full time he left his face alone for a little while before recommencing scratching again. This has continued for four years with ongoing trips to the vets. About six months ago he started scratching his back in between the shoulder blades. This coincided with the site of an injury - a cut about an inch in length which was glued back together and had fully healed with all fur grown back for weeks before he started the scracthing. I cannot get him to stop scratching and he is damaging his skin. He has dry skin. He is a nervous cat but is quite happy at home.

Things that have been considered/tried:

- allergies - he is on allergy food and has been for a year, its made no difference.
- stress - antidepressant tablets - these made him lethergic, constipated and miserable and didn't stop him scratching
- feliway plug in - makes no difference
- dressings/barriers - he just scratches until they come off
- softclaws - he scratched so much whilst wearing them he still managed to do damage

I asked if he could have his claws removed and got told this was illegal and cruel. I am at my wits end trying to stop him scratching and have spent a fortune in vets bills that have achieved nothing. please help as i do not know what else to try and am worried i will have to consider having him put to sleep as its not fair on him

Sounds like you've done a lot. The only thing I can think of is he's allergic to something other than the food. Do you use scented litter or air fresheners? I'd take a look at that. Good luck!

What kind of allergy food is he on now? We might have some better recommendations for you to try.

Have the vets considered environmental allergies? I know antihistamines have been successful with some cats.