PMR and depression

Has anyone experienced increased depression and sadness on prednisone for over a year? I am currently on 4mg, down from 20 mg. I have had a few flares and recently had a bout of sciatica. I am suddenly overwhelmed with even simple tasks. I’m an artist and stopped painting to spend more time being physically active and gardening. I’m an introvert but a good listener so people tend to unload on me while I hardly get a word in. Afterwards I’m exhausted. I’ve been on a low dose of sertraline for years. Maybe this isn’t PMR issue?