Air sac at wrong end...HELP!!

[Heidisgran]

just the last few days so it can develop a nice air sac

 

[HanLills777]

Thanks for the replies, I'm slightly confused though as when I googled it said lower the humidity as the heat will evaporate the moisture in the egg quicker and the airsacs will grow? Last year I had it at 45% all through incubation till lockdown but only one duckling hatched itself, I assisted the other 6

 

[HanLills777]

Also there were two eggs today that were going grey on the shells and when my TA went to look she smelt a very strong smell (I'm bunged up with cold so could only faintly smell it) candelled and there's nothing, but will they have affected the others at all? I resisted candling on Monday and Tuesday because of my cold otherwise I'd have caught them sooner but couldn't risk not candling today (I washed my hands thoroughly and did it quickly to avoid passing anything on) of the 14 left after the smelly ones were taken out 12 still had movements but again airsacs are small, two had no movement and I candlled for a while to double check and have removed these for fear of them getting grey and smelly too, does it sound like bacteria?