yes, that is wayyy to skinny. Get your full records from the current vet and get a second opinion immediately.
Increase the protein and carbs in dog foos. May require swithcing the food he in on. Here is a good website to compare the content of food. Stay in level one or level two foods.
Here is a website to look at, view the content of diffrent foods.
For good weightgain, I suggest switching to Natures Balance Sweet
pot. and fish- my dogs were picky too, but they love this food. It smells like fish so much they gobble it up. Buy a small bag and test it out first. Feed as treats, then start integratig it into your food.
Here is a good link for how to switch dog foods if you need it:
When they are being extremely picky, poke a hole in a fish oil capsule and squeeze over the food. Its great for them, bones, joints, skin, ec…. and makes them eat it all!
Also- supplement with "Nutrical" a puppy supplement with high protein for muscle growth. I still have to use it on my 5 year old because he just wont eat.