I have had my device for almost 3 years now. But I recall my arm being quite bruised and stiff after surgery. And, of course, I was told at the time I could not raise my left arm above shoulder height, shrug my shoulders or reach behind myself for 6 weeks after surgery. I was to avoid any forceful movements using that arm, and no heavy lifting (no more than 5 to 10 pounds), pushing or pulling. These restrictions were meant ensure the device had sufficient time to anchor in your heart. But, hopefully, at your follow-up appointment with your clinic/physician, they review some gentle arm and shoulder exercises.
Having said of all that, it is important you still gently move your arm/shoulder to avoid developing frozen shoulder syndrome.
I think your arm is still very much healing as is your incision site. And I know it can be frustrating and feel very isolating to be going through this. But you are not alone. Every member of this group knows exactly how you feel. All of us have traveled this same road.
Healing takes time. Use the gel pack to reduce inflammation and swelling. Take pain relievers such as Tylenol. I also used gentle heat, with a towel between my skin and the heat (I use a reheatable item called Magic bag. It is filled with wheat, of all things, and releases a moist type of heat which penetrates better. I heat it in the microwave. The great thing about it is it's warmth slowly fades and you do not have to worry about falling asleep with it on and possibly getting overheated or burnt. You may be able to get this off of Amazon.)
You are already half-way through your recovery period. Try to be patient and be kind to yourself. Things will get better.
Take care.