Hi smallzoo. Welcome to the forum.

I'm not a doctor and I have no medical qualifications so use your own judgement with anything I say here!

I've had on and off testicle pain for the last 40 years.  Sometimes the pain has been caused by an infection with the tongue twisting name of epididymitis which has required antibiotics.  But sometimes it comes for no reason, antibiotics do nothing, and then it settles back down again. I had a clear ultrasound with nothing found a couple of years ago.

You also mention the pain has spread to your perineum.  This could be referred pain from the testicles, or it might be prostatitis.  I know you had your prostate checked a year ago, but I think it would be wise to have it rechecked - maybe get a PSA blood test. 

Or it could also be a urinary tract infection. There is some evidence that cranberry juice can flush out bacteria from the urinary tract.  Even if it doesn't help, it won't do any harm and tastes very pleasant so you might like to try it.

These days doctors seem very reluctant to prescribe antibiotics which might be why the GP is suggesting painkillers to see if it settles down again.  If ibuprofen alone isn't helping, you should also be able take it in combination with paracetamol - just as long as you don't exceed the max daily dose for each painkiller.  If in doubt, check with your chemist.

I'm so used to having these symptoms that I generally leave it for a couple of weeks before telling my GP - unless the pain is very severe.  I think you should give it a week to see if it settles down and if not, then phone your GP again. Don't forget to ask for a PSA blood test.