I HAVE the answer to this. I suffered all the symptoms (groin pain testicular pain etc etc). for 18 months. Was examined by the great Mr Gilmore himself (definitely not a nice guy, ZERO empathy for his patients) and told, yes it was/no it wasn't his thing. Had all the scans etc etc, the most expensive tests around.
Having almost resolved to a life of pain I went to see my local osteopath about an unrelated problem, mentioned the groin pain, he diagnosed it in three seconds and fixed it in another five. I'm not joking!
In all probability your sacrem is stuck out of line. My laymans understanding is that because this is mis-aligned, the tendons that pass through it pull on your testicles/ groin and cause the pain. Simply applied and totally painless pressure from him fixed it. He tells me it is always missed by the scans as they are looking for trickier stuff.
BUT WAIT. It gets better. Once it has been stuck it is likely to happen again. You may have a weakness there. But do the following and you can fix it yourself.
Its called the frog. Lay flat on your back. Draw up your knees until your feet are flat on the floor. Now let your knees open and fall apart sideways (Like a frog). No need to push down, just spread 'em as far as they will easily go. This rotates the hip in the sockets and frees everything up.
I am NOT medical and this may not fix you. But it has fixed half a dozen buddies who, like me, were pretty thrilled at the result.
If you are really grateful send ten bucks to firstname.lastname@example.org
. Every 10 bucks goes to my osteopath.
Really hope this sorts it