Well first of all, WELCOME HOME!! We are your local and far away collection of body buzzers. Used to be b u t t buzzers, but now body as we have to recognize some of the battery/computer devices are implanted in the tummy, in the chest, and other places. Mine is a Boston Scientific model implanted June 2010 and I have not noticed swelling or pain regarding my upper right buttock implanted device EXCEPT when I lie on a hard surface, like wanting to look under the car for something so "on the ground I go." If I roll "Just Right" I know I am lying on that miracle device and if I remain in that position too long.... IT BECOMES SORE, pretty sore indeed. I have not noticed swelling from such an event, But, I can imagine repeated such behavior could aggravate the situation.

Is it possible some form of this issue is affecting you somehow..... even maybe if it doesn't come to mind right away? Think it through... maybe pressing up against a chair back in a certain way, a wall or file cabinet or car seat in a manner that may seem benign but causing the symptom you are feeling. If none of this comes to mind, then I reckon a visit to your pain management doc may be in order to have them opine whether anything is amiss with your unit which might cause the issue. Theirs is the best advice usually anyway unless there is some easily correctable environmental experience such as my silly crawling around under a car [well, I used to do that quite a bit, repair our vehicle when money was slim and electronics had not taken over the engine compartment].

No doubt someone of our other buzzer experts here will chime in regarding other possibilities.

That is what I have for now except to write "Thank You" for making yourself known here among us!
Mark56