@mjv96469
I have to be careful here to not give medical advice just pass on my experience with this.
I am on my 3rd ICD/Pacemaker and have had one since 2006. I think I have experienced all you can experience having one.

First, you just had the implant and your heart and area is going to be very sensitive. If you had wires put in latent or screw in you heart could be irritated from the surgery which could cause irritation. Another is stress. You just had surgery so stress can cause (from my EP) AFIB, PVCs, PACs, etc. My EP stated stress is one of the causes of AFIB. It is common to have high stress after a ICD/Pacemaker surgery.

You mentioned sleeping on left side. If you had a device implanted with wires how you sleep and what pressure you put on your device and wires could affect your heart. I know this because of so many incidents of AFIB, PVCs, PACs and the causes.

AFIB is hard to deal with both physically and mentally. I too was told by my EP that the biggest concern from cardioloigst with AFIB is the increase in risk of blood clots. Thus the Eliquis as blood thinner.

I am not familiar with dual chamber pulse generator. Does it have wires? Do any of these wires go into your Atrial. If so then they are going to be irritated and also by where you sleep the wires can move with pressure and maybe cause so irritation as the device and wires have not been in long enough to have what they call encapsulation. Which is the body putting a covering over of the foreign body to protect it. That takes some time to do.

Regarding sleeping. I really have found ways to sleep that don't put pressure on my device. I can feel the pressure and it is uncomfortable. I found by having my arms in certain places when I am sleeping on my side prevents the uncomfortable feeling around device. I also can feel the wires push upward when on my back. I found when sleeping on my left side I get the most pressure on the area of device as it is on left side so you have body weight pushing down on left side.

It is sad to hear your device manufacturer was not more helpful. This is not what I have encountered with Boston Scientific.