interesting... sounds like you must have had some really light headed spells. I'm a little curious about how the dual chamber is used for that. I have a dual chamber for Paroxysmal AV block.
I've had my PM for 4+ years. I have some soreness in the shoulder that I think is mostly muscular. Note this pain is in the upper shoulder .. well above the PM. I noticed I still wash my hair with my right hand only; a habit I picked up just after the PM since I was not suppose to raise my left that high for the first 6 weeks. It is quite amazing how habits get ingrained. The other issue I have is an insane itching around the PM when I hike (backpack). This seems to be caused by the strap pushing against the PM as hike. It feels like the pushing causes micro tears in the muscle/skin around the PM. It hasn't bothered me enough to have my wife modify the pack design.
I can't say that I've tried to split wood, but am fairly active.
So, I can't say I've had what it sounds like you have.
If I recall correctly I did a 9 day hiking trip about 6 months after getting the PM. The itching was the only issue. -- note the pack is likely 35-45lb and we usually hike either hills or mountains.
I worried quite a bit about pulling out the leads. I believe they expect the scaring to hold the leads in place.