Pain in right testicle at Orgasm

Hello everyone. I am a healthy 19 year old male, virgin by choice (lol). I've had a unforunate problem the past few years. It doesnt happen everytime, but often enough to cause to me post here. When i masturbate which is fairly often lol, but not everyday, if i last over 15 minutes, my right testicle seems to move up out of my scrotum and if i try to orgasm i either cannot, or it hurts alot. Sometimes, when my testicle moves up and out, i cannot orgasm, or i lose my erection (most likely from nervousness on the problem). I believe i had an undescended testicle as a baby but it was fixed if i did. It may also help to know that my left testicle doesnt seem to move at all during arousal or orgasm. Best i can tell, it may not "work" lol. When the right one moves i can push it back into place, often with some discomfort. I have spent the past months trying to rememdy this problem, as i am in the dating world for the first time. It may help to know the cause, by a type of "cure" i've found. This may sound graphic, but it seems to be the only way to not have this happen. If i use a anal plug, there is no pain at orgasm, and the right testicle doesnt move out of the scrotum regardless of if i last longer then 15 minutes. I figure the added pressure of the toy, may cause certain muscles to contract and keep the testicle in place.
This may be my last chance for a real remedy. It's embarrassing to tell someone i love that i will need a toy to keep the orgasm they will give from causing almost blinding pain. Any advice on a remedy will be great thanked. By myself and my future wife. Thanks again.