If you would like to test for coeliac disease, you have to keep eating gluten! You can ask for bloodtests, but these are not 100% reliable. I suggest you to do them.
To fully rule out coeliac disease you'll need a biopsy of your small intestine. For more info see: http://en.wikipedia.org/wiki/Coeliac_disease
My question was what you meant with D and B levels, but I understand now you meant vitamin D and B12.
You need to test for B12, I don't know exactly which methods are best. Also I recommend to test for Fe.
It's important to keep monitoring your vit D levels. Too high is not good (and too low also not).