If i were you I would be harassing your vet for a referral ASAP or doing my own research to find a better vet. It sounds like your problem is very serious if he's throwing up everything but treats and refusing all food and I would not wait very long to see someone else. I think at this point you need a vet to diagnose the issue as it doesn't appear you can solve this on your own. I've heard stories about cats being fed Friskies their entire lives and living to be in their 20s, it doesn't mean it's a good option. The bottom line is treats aren't a complete nutritional source.
For 2 days I stopped the treats. I offered him dry food, wet food, etc. He didn't eat at all. The rest of the time, he's waking me up in the middle of the night, or meowing for something I'm tryng to avoid him eating (the treats). 2 days w/o eating is holding off long enough. He HAS to eat something and I've tried very hard not giving into his demands, but it seemed after 2 days of not eating, I wanted him to eat something rather than nothing. Now, I'm adding vitamins to the treats. I have given him good quality treats - he threw them up too! What it sounds like to you is not that way it is. So please, I'm doing everything I can possibly do for HIS benefit. All those good quality treats? you recommended, he throws them up. I'm waiting to get a referral to a 'more qualified vet' and an ultrasound - in the meanwhile - he has to eat. He's definitely NOT ready for a feeding tube.
So, if you'll excuse me, I'm tired; tired o staying up all night with him meowing for food because he's hungry refusing EVERYTHING else except treats, and so yes I'm temporarily giving in to his demands because a) eating treats/vitamins is better than nothing and b) if I don'g get some sleep, I won't be in anh\ condition to keep at this. I've also done a lot of research on my own and it's not true I've hard stories of cat being fed just treats for years because they won't eat anything else and they are surviving and at least healthy now.