Hi Suzie,
On Camino, maybe control your walking hours each day so as not to get too worn out. Have days off frequently. Burning calories is one thing, but the extra stress of walking every day for weeks on end is a whole other level of effort for your body to deal with and to recover from. Weariness can build up and wear you down, make you vulnerable.
I carried trail mix which I made myself and "energy" bars which I found in the breakfast cereal section of Spanish supermarkets (stock up in the bigger towns). Some of the energy bars are chocolate-coated! Crazy for a normal breakfast but loaded with calories for snacks. 200 calories an hour isn't an unreasonable amount. My phone app tells me I burn more than that per hour on my daily walk.
You'll have to keep an eye on your iron intake if you're anaemic. There's iron in dark chocolate - many walkers eat it for the calories alone. I took a good quality iron supplement while on Camino, as I'm vegetarian and I was concerned on my first Camino because I heard that the Spanish diet is very meat-heavy and expected I might end up on a patchy diet which wasn't as varied as I was used to. Non-vegetarians often don't realise how rich fresh food (salad!) is in minerals and vitamins. You'll have to work at it to get a varied diet of fresh food on Camino. Cooked vegetables can easily have the goodies boiled out of them. Cooked veggies no substitute for fresh. I used to ask waiters to combine ingredients from different dishes on the menu so I ended up with a properly interesting salad. You'll find some interesting items in even smaller supermarkets along the Camino - cans of chick peas, jars of chick pea or bean-based "stew", and large jars of crunchy salad! Yes salad in jars - bean shoots and other selected goodies in a mild brine. Pour off the brine and dig in. Weird but delicious and surprisingly good stuff. You'll eat a lot of oranges on Camino - every second bar has an elaborate orange-juicing machine. Fresh. OJ. Never mind the sugar, you'll burn that up, go for the vitamin C to help your bod to repair itself every day.
When I got back home, I had a medical checkup. I told my doctor about muscle stiffness, tightness while walking, she said "magnesium!" Next time I will take a very good supplement which contains magnesium as well as iron - in fact I take a tablet every day now. On Camino, I assume that unusual demands on one's body create these extra needs, which can result, it seems, in these unusual temporary mild deficiencies. As a vegetarian on Camino, my diet was inconsistent and not as varied as I was accustomed to, because the culture is different. Protein is easy, minerals & vitamins - not so much. Your diet is so specific that I suggest these few extra strategies.
Buen Camino, - Mike