Everyone with autoimmune disease from time-to-time will feel drained, unbelievably tired and sometimes heavy eyed. Coeliacs may feel like this before they are diagnosed, just after they are diagnosed or when they have 'lapsed' (please try never to lapse and think that it is safe and all right to eat grains) or if they have accidentally ingested gluten.
Firstly, it is important to overhaul the diet and to see whether there is any possibility that gluten is being consumed in some guise or other .. sauces, stock cubes, drinks of any description, instant meals .. check everything, every label and if you are not sure of any of the ingredients - don't eat the contents. Of course, you can always check here with us as someone is bound to know if it is safe or not!!
Our best defence will always be knowledge, of which we cannot ever have too much and with that thought in mind - I would like to add a link to a site that I came across by accident as I think you may all find it interesting. The site is called 'Doctor Yourself Dot Com' - it is a site that has been created for Homesteading Health; here is their page on Chronic Fatigue: