She still won't eat

Martha won't eat.

We visited the vet yesterday, and thankfully she's gained 2 pounds since the last visit, last week. But her appetite strays towards the Tostitos and Dorito food group. Her appetite for nutritious food is negligible. I've posted to PSG-L, and received many good suggestions. All these, including recommendations from the vet, have failed so far.
Liver, bleech, she spits it out.
Canned food of all types, nope.
Cooked ground turkey, no.
Nothing pleases her, or entices her appetite.
Does she still have morning sickness?
Blood work and examination by the vet finds no physical ailment that could be causing this lack of appetite. He suggested we give her vitamin B complex and brewer's yeast to stimulate her appetite. I found the vitamin at the local Walgreens, and she had her first dose last night, but I can't locate brewer's yeast. I will try the local health food store today.