Gluten free bread isn't cheap anywhere and not very nice generally. Genius is the best I've tried though it's a little loaf with tiny slices.
Gluten free pasta and spaghetti is OK, I don't notice the difference from normal cheaper pasta and spaghetti though I'd recommend using it fresh rather than making batches of food, fridging it and reheating as it doesn't keep like that very well.
Different supermarkets have different offers on at times though I get most gluten free stuff I buy from Tesco. I tend to think of ideas which just don't include gluten products rather than buying the substitutes.
Do get used to checking labels though, partly for hidden gluten and things you might not realise contain it and for products not in the gluten free section which are still gluten free.
Have they done a test for coeliac? Seems like getting to a gastro consultant would help. If it is coeliac then there are also dietic services which could help. As, as said above, it's not just like an intolerance.
If it were me, I wouldn't be just taking a GP's opinion on something this.