Really, you have two issues: traveling with a group and perhaps not knowing Spanish (I don't want to presume). Spanish foods can be wonderful and healthily and you should be able to find stuff you like if you can identify it on the menu. However, if the tour folks have arranged your meals, you need to work with them, and let them know your dietary restrictions. I also would bring individual size protein shake powder and a few shaker bottles, so that you can get your lean protein in every day. Then, just look for the veggies.

eating overseas isn't that much different than eating out in a different city, except that many of the fodds are much better. you just have to remember your portion sizes and try to eat your protein first. every country I've eaten in around the world always has a fish or lean meat dish that was excellent.