Polish chicken getting bullied?? Cant tell by who though

[Cherrybeeboo]

Im a first time chicken owner and i have 3 bantam polish and 1 serama, everything seemed to be going fine the chickens have moved to their new eglu coop with 2 metre run they all eat and drink fine and they seem chill but today i got all of them out one by one to do a check and to keep them tame and on the last one i noticed a large bald patch in the crest which no one else had, it looks like its been pecked, this chick was the one most likely to definetly be a hen out of them all (no wattles yet, small, quiet) the thing is i have no idea who it could be like i didn't even know it was happening until today what do you guys suggest i do? All of them were raised together since hatch except the serama but the serama joined them when they were only 3 weeks And the serama is short enough i couldnt see them really pecking it much up there

 

[aart]

So how old are they, in weeks?
Is the bald patch on the back of the crest?
Could be a male is trying to dominate/mate.

 

[Cherrybeeboo]

So how old are they, in weeks?
Is the bald patch on the back of the crest?
Could be a male is trying to dominate/mate.

They are 7weeks, the bald patch is on the top back of the crest, im hoping its not a male thats trying to do it because i really cant end up with any cockerels

 

[aart]

They are 7weeks, the bald patch is on the top back of the crest, im hoping its not a male thats trying to do it because i really cant end up with any cockerels

Too young for that nonsense(probably).

 

[Cherrybeeboo]

Too young for that nonsense(probably).

I checked my chickens again and black beak one of the polish i thought might have done it also has bald spots in the same sort of area although much smaller and less noticeable, im pretty sure its my big one who i swear despite the hen looking crests has to be 100% male
They all stay out if his way especially the one who was pecked the most, i occasionally see him rear up and fly at the others, i think im going to have to get rid of him if it continues hes the only one without any bald spots.