It doesn't sound like there was a point trauma to your member, unless you are not mentioning it. You sound sad, so I wanted to tell you some info to help you get started.
The feeling of having to urinate after sex and the subsequent lingering pain could be from problems related to the pudendal nerve. I just want to mention the possibility of more advanced problems just in case, since you are having problems getting treated.
The pudendal nerve is the nerve that runs from the spine through the alcock's canal near your bottom, through to the exterior portions of your ****, testes, and penis to innervate them.
Problems along this nerve line can cause pain, numbness, or hypersensitivity along this nerve route. There can also be incontinence and sexual dysfunction.
I would suggest the possibility that there was some problem with it, and your masturbation session was when it really first presented itself to you.
Causes of pudendal nerve entrapment can include lower back problems (anywhere from L4 through S4) tugging on it, ligaments rubbing it the way, alcock canal getting smaller and rubbing it (scar tissue or by other means), piriformis muscle problems since it runs close to it, etc. It can even be from Femoroacetabular Impingement (FAI) or hip impingement syndrome.
Electrical pain, especially during or post masturbation, is something I have experienced myself from having pudendal nerve entrapment - including one episode of post-urination. Look up other symptoms, because soreness or pain are quite common when this nerve gets pulled or squished.
Note though, that there are many doctors that do not know about pudendal neuralgia, in both women and men. It's newer, but there are a good amount out there. Just find some, get second opinions, and insist on an MRI. The MRI is important because tumors (benign or otherwise) can take up room and squish this nerve. Try to find the cause of the entrapment (the squisher), if that's what it turns out to be, before you agree to any surgical intervention.
There's a lot to your body down there, so there's a lot that can be the cause. Don't give up.