i have seen ybs going out the loft for first time and not returning back for 3 to 4 days, you think its all over but they turn up, hope you get them back atb
hi nick, start cutting the protein back in the mix your feeding,feed the same amount as your doing every day but a mix with a lot less protein,content if you can get it where you are, atb
make sure there is good flow of air going in and out of loft, get them on multivit,and probiotic asap, if it is ornithosis you can treat with doxycycline, atb