@jathang I too have something similar due to low back injury in for which I was fused in 1990 L4-S1 and I have peripheral neuropathy of my legs as well. I do have decreased feeling when erect which interferes with ejaculation but it’s intermittent. You should consider seeing a urologist who specializes in sexual dysfunction especially at such a young age. You’ll need some testing that insurance can cover. John’s Hopkins or another large teaching hospital would be a good start. And you’re in luck that Dr. Rena Malik practices out of UofM hospital and you can check her out on YouTube by looking up her name. Good luck my young friend.