Help with my Dachsund's allergies?

[Kylie W]

Does anyone have any advice for me? My 2 yr old male black dachsund is losing his hair, has rashes in his armpits, and sometimes spits up plhegm. ive been to the vet and they have run blood tests and told me cats but since they were out of my life the allergies have not gone away. when we give him steroids its better but we cant continue with them much longer...
ok here is more:

we had allergy blood tests. it came up pos as cats. but we have completely removed all traces of cats from our lives. we have seen 2 vets. they do now know what to do. we give him fish oil everday. steroids every other day. we have him on specialty anti allergin food. he is energetic and happy other than the hairloss and rashes. sometimes he bites at his feet. we have not had any skin scraping done.