Hello- My Mom Has A Pacemaker Has CHF. Last Monday

Hello- my mom has a pacemaker has CHF. Last Monday (a week ago) she showed me a large bruise on her shoulder down to under her arm. It is on the side of the pacemaker. She DID NOT fall. All she said she did was lean against the door frame to step over a lip going into another room. The ER docs kept saying that she must have taken quite a fall. I live with her and would know if she had. Could it be the pacemaker? She says that it feels like its dangling a bit when she sleeps on the opposite side. Any answers?