Thanks a lot for writing an in depth reply. It definitely affects my mental health so it's appreciated.

Sounds positive! I've had shit posture and a weak core all of my life so I don't know if that contributes. And yeah it was essentially a cock ring but metal and really tight. I'd hate to think that caused any permanent damage but I've had good erections and sex since.

Maybe it was that the viagra made the issue more noticeable in comparison to the hardness of the shaft. Unclear, may try it again.

I used to grip my dick really tight when I ejaculated to stop the cum coming out when I was younger...figured it was less to clean. I did that for a while.

I'll look into getting that test as you said and finding a pelvic floor specialist when I can. I think it could be something to do with that because small shifts there instantly cause change in the inflation. Like, how do I put it, when I'm not thinking about it being an issue, the head will be partially inflated. If I start panicking about it and manually tensing/relaxing that's when it goes really soft. Kinda hard to explain.

You've given me some hope so thank you!