Remember Petunia this past summer, and her impacted crop, she had the formatted grain breath and all.
5 weeks she was like that; I gathered the equipment to do a crop surgery but had some delays due to my theatre nurse (BIL) not being available.
In the meantime I had drenched (dosed) her a few times with Anti Gaz ( 
https://www.drugs.com/vet/anti-gaz-emulsion-can.html ) which is used for colic and constipation, it helps to break up impactions.
I was also massaging her crop a couple times a day.
Then on the day we were going to so the surgery, I checked her that morning to do the massage and it was gone! To say I was freaked out would be a simple statement. I imagined I had somehow ruptured the crop and the contents were floating around in there.
But she seemed fine so I just kept an eye on her, and a few days later she went into a heavy moult.
Now a few months later she is looking great and I haven’t seen her crop impacted.
I can only assume that the Anti Gaz did it’s job and helped break up the material stuck there for over 5 weeks.
I would try some Anti Gaz and massage. Also limit her intake.