My 78 Yr Old Husband Has Last Stage Parkinson's &

my 78 yr old husband has last stage Parkinson's & Dementia & is bed ridden. When I was changing his diaper I noticed that he had a fluid filled blister on his penis. He has had one of these on his wrist that burst & took some time to heal. His Hospice nurse said it was a pressure sore,,,,but doesn't know what the one on his penis is.