I concur with your chiropractor, though not sure if a chiropractor should be doing it, instead a nutritionist is the best bet. This is exactly what weight loss centres do these days, in that they do blood tests and determine what works with your body vs. against it. Same thing... in that to change your diet, remove certain types of food and introduce others, you will find your general health as a whole will improve, which directly impacts depression and anxiety. Combine this with exercise, and well, you just about control anxiety and depression without the need for medication, let alone if you have learnt how to manage PTSD itself, which incorporates nutrition and exercise anyhow.