What medication are you on?

As for the jittering, I read somewhere it's due to excess adrenaline coursing through your body. They suggest going outside for a brisk walk or a run, which can be too much for me since I have low mood as well. I'm a beginner at yoga (I only started 3-4 weeks ago at the insistence of my husband so that I don't continually keep myself in the house) but googled some beginner positions that may relieve anxiety and even 5-10 minutes of trying to hold 3 basic poses relieved me of the jittery/shaking feeling and the heart pounding. Might work for you too? I was actually quite surprised it worked to be honest, but I was desperate at that point!