Just like people, pets can get sick for many reasons. Rico has discharge on his muzzle and this could indicate an infection in his mouth or his sinus. Many other causes are also possible. Not eating for 3 days is a long time for a cat. When pets don't eat well, its highly likely that they are not drinking well either. This can lead to dehydration and can spiral into many other health conditions. Roco needs to be examined today by the veterinarian. A physical exam will help to figure out the cause of illness. He may also need some diagnostics. He also needs to be treated symptomatically.
I hope he starts feeling better quickly and please feel free to post any additional questions.