My sons sick Beta Fish

Question
My son has had a male Beta for the last year or more and its always been very healthy.  It is in a one gallon tank with a little air filter with a blue filter stone in it, but no heater.  I'm sorry I don't even know how to check things like pH, ammonia and nitrite levels. We just noticed today that the poor little guy has black "crud" all over his head and front portion of his body. Its not sticking out or anything, its just as though all his colors have turned to black.  I have NO IDEA what to do and my son is in tears.  I've read so many different conflicting things, and none of them mention the fish turning black. I'm overwhelmed!  Please help!!  

Answer
Hi Jeanne;

How often do you change his water?
Is the water temperature warmer or colder than usual?
Is he eating?
Is he acting abnormally in any way?
Does it look like he has any swellings on his chin or around his gills?

Let me know as soon as you can......

Chris Robbins