If you want to use gelatin as a "protein powder", you might want to consider the hydrolyzed form, which dissolves without needing hot liquid.
I use gelatin for weeks at a time. So does Stabby, another paleohacker, and a couple more people if you check other gelatin threads. I personally don't make bone broth anymore because it's so stinky in my little apartment while cooking up!
There are no excitotoxins in pure gelatin products, such as Great Lakes gelatin. There are excitoxins in boxed foods that contain gelatin, such as Jello.
Another option, if you don't like the added ingredients in protein shakes, is to get pure milk protein, pure egg protein, or even a mix of the two. The two most well-known customized protein ordering websites (i.e. no sweetener, thickener, or flavor necessary) are Protein Factory and True Protein. Also, unflavored protein is available on Amazon, but sometimes more expensive and not able to be ordered in small quantities. Also also, organic unflavored protein is amazingly expensive, and a very rare bird as well.