I notice after my runs (though only 4-5 miles) I cant stomach solid meals. Go for liquid meal replacements (Muscle Milk tastes amazing but can be price), Protien powders (I use Optimum Nutrition Whey) and mix it with milk or with gaterade powder(better after runs/workouts). Eat BIG BREAKASTS, you might be overlooking that, its seemed to help when i need to eat more. And keep eating more often, smaller meals to stoke your metabolism constantly.
Get the proper nutrition pre during and post workout if possible... Carbs + Protien. You could make shakes with gaterade powder and Whey protien, about 2g of carbs for every 1 g of protien and mess around from there for proportions.
Peanut butter and almonds pack in alot of calories, and i seem to never notice how much im eating, they may help with adding healthy fat and calories in your diet.
Before you sleep, try having Cottage cheese. The Casein protien is is absorbed and digested slower than most, so it helps to ward off some muscle catabolism.
http://www.stumptuous.com/cottage.html
Theres a page with lots of ways to incorporate cottage cheese into foods.
My main advice for gaining muscle besides Eating ALOT , and then alot more. Would be to incorporate some sort of weight training, which would give your muscles the stimulus for growth... as well as get more than adequate sleep, to allow recovery!
Hope this helps a bit, ive gotta run out for a while.