I'm new to raising chickens. I've been letting my chickens eat unlimited amounts of feed not realizing that I wasn't suppose to. They will turn 4 weeks old on Saturday. I just started the 12 on 12 off today. Do you think it is too late to prevent CHF in week 6? My medicated feed says I can feed them from start to finish with it. Any ideas on this? Should I switch to nonmedicated?