Hi Nick, sounds like a radiculopathy (referred pain from either a disc problem/ nerve problem or some other issue. You should get an MRI or at least CT to confirm or rule out these or other possibilities. Dont bother with xray as they dont help with disc/nerve or soft tissue problems.
Kidney stones or renal colic can also cause symptoms like these, however any Dr or specialist would still need to do scan to help diagnose anyway. I have L4/L5 hernations so I can empathise with you re the pain etc. Hope you get an answer soon. Also remember that severe pain can cause and be caused by muscle spasms.
You didnt say whether you had seen any MD yet. The area that controls bladder, bowels and that groin area is specifically L1. Since your testicals are in that same region you might wantbto see someone sooner than later. Good luck.
Have you ever had a disk herniation/?
I have,.10mm. in the L4-L5 8mm L5-S1 .... and the symptoms you are describing are just like my back injury i had at work back in 97... L4 L5 area of the spine,,, made that nerve root flare up so much, it started in my big toe on the left side.. pain in my outer lower calf of right leg...left outer side of thigh... left buttock cheek.. and... left testicle ,, felt like someone is squeezing it!
all happened more when that area of the spine flared up..
i honestly hope you do not have what i have...
best of luck....