Generally quill loss is caused by quilling, mites, bacterial infection, fungal infection or stress/ recovery from stress.
With stress, we would expect to see some other signs. Change in behavior, digestive issues things like that.
With bacterial and fungal infections sometimes the only sign is the quill loss.
And with mites, usually there is the crazy itchiness.
What can you treat at home within reason? Stress, if you can identify a source you can deal with it. Mites, bacterial or fungal infections need to be evaluated and treated by a vet.