Kidney Swelling and Pain

I'm in my 50s.  My kidneys feel large.  I noticed this last year.  When I run my hands along my back, I can feel them bumped out.  My lower back also hurts a lot, and has been worsening over about ten years.  Now it gives out and is very uncomfortable, so I thought it was a spinal problem.  But black and white X-ray yesterday says lumbar spine is okay.  The only other thing is about three years ago, I had foam in my urine for a few months.  My triglycerides were high at that time, so I thought I had nephritis, from reading about symptoms.  But when it went away, I forgot about it.

I have not posted in here before.  I don't know much about kidneys.  Other than the foam in urine, I never thought I might have a kidney problem until I could feel how big they seemed last year.  I always thought the pain in my lower back was normal spinal arthritis, until it started giving out and the pain worsened.  But the X-ray doesn't show any back trouble.  This shocked me.  And then I worried that maybe my mental confusion and pain in my back might be from kidney problems.

Does this sound like a kidney problem?  Do kidneys swell up?  Does kidney disease make the lower back hurt?  If the kidneys malfunction, does the body sort of get poisoned to where you lose your mental focus and get confused?  Thank you for any feedback.