I Am A 36 Year Old Make, Slightly Over Weight

I am a 36 year old make, slightly over weight but generally well although I have suffered from lower back pain for some time and not sure if it's related to the issue I'm writing about. For the past few days I've had the sensasion of vibration in my scrotum. It kind of feels like it's my left testicle. It's a regular pulse occurring every 4-5 seconds. Each pulse lasts a second or so. It's quite faint but very noticeable when I'm sat or lying still. There is no real pain and I've done a self exam and don't feel anything unusual. I've not been overly active, sexually but also not abstaining. I guess I would say my sexual / masturbatory activities are as they always have been.
I'm not as active physically as usual but this is due to recovering from a TR Achilles. And probably unrelated but am seeing a doctor about sudden onset double vision (wandering right eye) but the vibration tingling testicle is the thing I can't find any info on. Any ideas.
P.S I'm not a hypochondriac.