Feeding a Picky Cockapoo?

I got Sparky when he was 2 months old and he was fed dry food, Purina Pro Plan. Eventually someone gave him human food and he didn't want the dry anymore. He was loosing weight so I found wet dog food, Purina Pedigree, but he would only eat it if I fed him with a spoon. He is now 2 years old. I bought the same dry brand and he has gone 11 days without food. He would drink water, but then finally he ate, not much, but some. I've tried Merrick, Science Diet, Solid Gold, and now Nutro. He won't eat and even though he is still energetic around me it's starting to worry me. Any ideas?