Csalamon, I feel for you. Traveling with a food intolerance or allergy is difficult. I have Celiac Disease. While my symptoms aren't life-threatening, as yours are, I cannot risk ingesting gluten while traveling. I don't have specific suggestions for restaurants, but I will share what I do to prepare for our trips.
In the months leading to a trip, I get on Google Maps and look for restaurants in the cities we will be visiting. I then click on each restaurant's website and go to their menu. From the menu, I can see what they offer that I could eat and what will cause possible cross contamination such as frying onion rings in the same oil as french fries. I then make a list of restaurants for each city and save them on Google Maps. It literally takes days to do this and find a couple of restaurants in each city. Depending on how long we stay in each city, we may return to a particular restaurant a couple of times. I'm totally OK with eating the same thing a couple of times if I know it's safe.
I also use a couple of apps built for finding restaurants that have gluten-free food. Maybe there is such and app for shellfish allergies?
Some cities are particularly difficult. In those cities we frequent grocery stores for meals. Luckily, my husband is easy-going and is willing to do what I need to do in order to eat a safe meal.
Since a shellfish allergy is not as common as some other food allergies, I'm not sure how many replies you will get for specific restaurants. You may have to do the tedious work of looking up the menus for restaurants. From each menu, you should be able to see if they have any shellfish in their kitchen.
Good luck, and I wish you a safe trip. I know how hard it is to travel with a food intolerance/allergy!
