It’s a little hard to see in those pictures. I’m glad she’s doing better!
You have to be really careful when administering liquids straight to the mouth. If they breathe it in by accident it can kill them. The oesophagus is under the tongue on the bird’s RHS and the trachea is directly center...
Could she be panting because of the heat and perhaps the stress of bumblefoot treatment? Especially if she is moulting, being handled is probably no fun at all.
Is she making any gurgling, wheezing or sneezing noises? Any discharge or bubbles around her eyes and nose?
If you can feel her...
The bumblefoot and the breathing are not necessarily related. It's good you are getting on top of the bumblefoot. Check her crop to see if it is empty in the morning and if you can get a picture of her poop that would be helpful. Does your hen lay eggs and when did she last lay? Does her comb...