We're having the same issue! My daughter, also 9 months, will only drink her morning bottle (refuses the other 3) and BARELY eats any food. I know its not her teeth because she already has 7 and the symptoms are different. I read that it could be a phase, a new independence OR tat the baby's growth is starting to slow (which usually happens towards 1 year of age). Whats troubling me the most is she still eats great and takes all of her bottles at daycare!
I guess this wasn't helpful to you other than to know that someone else is having the same issue with their baby :) Good luck!!!