I am currently living in Nicaragua. When I first moved down here, I
noticed that I lost weight pretty quickly, probably a result of the
diet change as well as lots more physical activity.

I have now started to exercise, and am wondering about the nutritional
content of my diet. I eat rice and beans with fresh white-corn
tortillas twice a day.

Can you let me know (roughly) what I am eating in terms of calories,
fat, carbohydrates, and vitamins or nutrients?

Thanks!

It really depends on the type of rice and beans, as well as the tortilla.

Check out http://www.nal.usda.gov/fnic/foodcomp/search/ 

Excellent site.