If you feel she is greatly suffering, then it may be time to let her go.
You can try soaking her in a warm epsom salts bath to see if that gives her relief. It's hard to tell what she's suffering from and often we don't know unless we lose them and perform a necropsy to see what was going on.
I'd like to see a few more photos of the vent, can you get 1-2 that shows the vent directly instead of from the side?
Look her over for lice/mites while you are treating her and make sure her crop is emptying overnight.