It has been 7 days on 9.6% doing the second highest dosage-4.73cc/gal. of water. It started with blood in the stools, which subsided somewhat, but my rooster who had it the worst is now very groggy and foaming at the mouth. There is no more blood in his stools, but I can tell he hasn't eaten much by the white and bright green. There is still a minimal amount of blood in other chicken stools though.
I use Corrid-V in EVERYBODY'S water. I had a horrible outbreak November a year ago and lost 12 birds in three days. The Corrid-V stopped it and saved some birds which were pretty sick. So now I keep it on hand.
You should see improvement within 24 hours or so from my experience. Yes, go to the normal dose now as above IMO.
I don't know what the foaming at the mouth is, but if he is not drinking you will have to take a syringe with some of the medicated water (mix-not pure amprolium) and put it alongside his beak so he can drink it (not pour it down his throat or anything).
I was given Baycox by my vet when I had an outbreak last year. It is only a 2 day treatment and they went from being obviously sick to looking healthy after the first day. I was very impressed with it.