Can anyone advise me

How long do I have to eat wheat before a biopsy and how much do I have to eat?

from
http://www.celiac.ca/?page_id=128


A biopsy for celiac disease looks for changes in the small intestine that happen when you eat gluten. If you have stopped eating gluten, your intestine may have begun to heal and that can lead to a false negative result (a negative biopsy even though you have celiac disease).

In general, the recommendation is that you eat the equivalent of 4 slices of wheat bread every day for at least 3 months before a biopsy. Your doctor may have different recommendations for you, based on your own medical condition.

We don't know a lot about how long it takes to redo damage after your gut heals, so this might not be enough time to re-introduce damage.