Making a Mountain out of a Mole Hill

I know I've written a lot about my dog on here, but I promise I'm not one of those freaky obsessive dog people. (Well, maybe just a little. I can't help that I married a man with such an awesome dog. What an added bonus to the arrangement!) Anyway, Rudy's been acting strange lately, so here's a concern of mine concerning Rudy:

My dog won't eat and he has something on his nose. I'm choosing to believe the two are not mutually exclusive and are entirely related. (Matt's upset that the previous sentence is redundant, but he doesn't understand the purpose of repetition for emphasis. Only an English teacher would pick up on that.) Point being: I'm concerned about my pooch. Let me further explain...

Usually, Rudy eats right away in the morning and promptly again at 5pm. However, lately his breakfast sits in his bowl until 3 or 4pm in the afternoon. He'll eat eventually, but this is very odd behavior for an 80 lb. pit bull who is always hunting through the kitchen for more food.
In addition to that oddity, there is also this weird spot next to his nose that keeps getting bigger. It's not a big raised bump, just a flat, white, round spot. It started out small and has grown to about a centimeter in diameter.

It seems strange to me that both of these problems are occurring at the same time. So, I'm putting two and two together and coming to the conclusion that the spot is cancer and he won't eat because he's sick. See how they are entirely related?!? Okay...a bit irrational, I know...but what if it's TRUE?!