Dog won't gain weight.

Our boy, Zidane, was born May 19, 2009, which makes Zidane almost 18 months old. He has been a finicky eater since the day I brought him home but I was able to get him to eat kibble mixed with canned food. He got to the point where he just wouldn’t eat and would wait to see if there was anything better. I knew and everyone told me he was spoiled and finicky and I should put the food down and if he didn’t eat it just take it away till the next feeding. I did this and he’d sort of eat but only enough to not starve but certainly not enough for a dogue that is still growing. He got down to 108 lbs. and his spine, hip bones and bone on his head were protruding. Since he wouldn’t eat any kibble or canned food, I switched him to raw. He loved it for about 3 weeks and put weight on to 118 lbs. Now, he won’t eat that either. The only thing he eats is Natural Balance rolls, raw food but in freeze dried form, boiled chicken, hamburger patties, cheese and eggs. It all has protein but he is not putting on weight. He’s only 112 lbs. and I remember his breeder telling me his dad was 150 lbs. at 18 months old. Zidane is strong, full of energy, wants to play, and so on so I doubt he is “sick.” But I’m worried that he is not filling in and quite tired of having to play the "eating" game at each feeding.