AIHA strikes fear into my heart. I've had 3 of my own go through it. Seems cockers are more susceptible to it than some breeds. The symptoms always seem to be vague and varied. I've gotten to the point, if ANYTHING seems off, check the gums for a healthy pink color. If gums appear pale, white or greyish - run, don't walk to the vet. We caught two of ours in time to save them, but the third dog was on a low dose of pred for back issues and it apparently was enough to mask his symptoms until it was too late.
It's great that they were able to pull your dog through this.
So very sorry for your loss. It is never easy losing them and each one takes a piece of our hearts with them.