Hi,
I'm extremely sensitive to anything gluten. I will literally throw up within a few hours after I consume it. I have coeliacs disease. Go to this site and print the following
http://www.celiactravel.com/cards/spanish/ and also add the other allergies you have - it will help you in the restaurants.
Another really good site is this one:
http://www.celiacos.org/gluten-free-spain.html
Spanish people are beautiful and super helpful, they will help you all the way. I walked the Camino in 2011 and they turned themselves inside out to help me. I am sure there are Spanish people with your condition, so even tho this (garlic, onion and bread) is a staple in the Spanish kitchen you will still get the help and support you need. My only advice is that you always try to start the conversation with some Spanish (maybe you speak it already) as they really appreciate you making that effort. You can have omelettes with or without the potatoes and then some (plenty of choices),, many dinners with the best salads you can imagine (in the pilgrim menu). They have cooked special dinners for me so many times (I love Spanish food after my 2011 Camino) and you also have the options of cooking on your own in the various albergues (not all of them).
During the days, I advise you to pick up nuts and fruit along the way cause you never know where you'll get to eat the food you need.
So you'll be fine, just make sure you know how to communicate your needs.
Here is a warm salad they made specially for me
(I'm hungry now).
I'm heading back next week and have already spoken to a few places about my "limitations" and been given options, so lots and lots of understanding.
Enjoy!