Malfunctions

I was diagnosed with Acute Peripheral Neuropathy, and lost essentially all feeling in my legs. Fortunately, my dick, ass and testis are all still functional and I can feel them close to the same as i used to, well I don't know about the anal sex play felling any different that's relatively new as i just started practicing that as a result of the problems caused by the P.N. but as it turns out I'm still having issues involving erections. I'm hornier than a high school boy with a pair of his crush's panties, and my stimulations have become more intimate but relatively same sensations i was accustomed to before my body decided to attack itself. my issue is my dick gets hard as a rock for maybe 5-10 mins into my FunTime then soon as i feel the tingles of an orgasm it immediately goes as limp as cooked spaghetti and my urethra feels rock hard. I'm wondering if it may be my condition or overstimulation considering I need to rub out up to 3 times a day for relief... my orgasms as strong as they are, produce very little spunk even when I'm at the ass end of one of my week-long tantric meditation and edging marathons which I do every other week or so and it causes almost a blue ball feeling with an itchy urethra, almost feeling like I need another release almost immediately after already having one. is there anyone familiar with these issues who can point me in a direction to help, or give me some pointers?

Always horny,
Misfit-Man