I Have Been Hearing A Hissing Noise In My Head

I have been hearing a hissing noise in my head for a few days. Or it sounds like running water. I am 72 years old, in pretty good health, fairly active, and have chronic pain in my neck, lower back, and knees. I have a pain pump in my r/f lower belly with Fentenyl (sp) in it. It's been there for 5 years. It goes into my spine via a line about the middle of my spine. M neck also hurts a lot all the time for the last 4 months or so because of arthritis there.