Everyone is different. If you want to know what is going on,
get the nutrient levels in your blood checked. Most people are
deficient in something.
Magnesium is worth trying, the citrate that was mentioned is one of the
better options.
A snack after a long ride is not a bad idea, 10-15 grams of protein with
some carbs.
Fruits that have enzymes are good for healing, pineapple, kiwi, papaya, that sort of thing.
Have them with any meal that has a decent amount of protein.