Ugg, sorry you're having such a tough time finding something that works. I wonder it it just didn't agree with another product you were using. Also, have you considered your water might be making your hair feel dry and brittle? How hard is the water in your area? Do you use a shower filter?
That MHC product is definitely not protein free. The glycine soja is soy protein and I believe seawood is also protein, but not positive about that.