Pacemaker moving

My father had a pacemaker put in 8 months ago. It has recently slipped several inches and is moved in toward his armpit.  The skin looks broken and it is rad and swollen looking like infection.

He is schedule to have a new unit put in.  Is this type of circumstance common?  This is 8 months post surgery

[Cleveland Clinic]

This occurs in about 1 % of patients.  It is as you suggested called a pacemaker pocket infection.  The system must be extracted, both the pacemaker and the leads.  He then has to be treated with antibiotics and have a totally new system put in on the opposite site.  This is a serious condition and must be dealt with in exactly the order that I describe above.  There are no shortcuts to this.  Don't let his doctors try to take out the old pacer, leaving the leads behind, and replace it with a new pacer that's buried below the pectoralis muscle.  That's sometimes done at small community hospitals where this practice is still not uncommon.  It is the wrong thing to do for sure.