Does persisting neck pain or neck diseases causes erectile dysfunction ?

Most likely, not ...: As young as at 26, age-related neck pain & disease is less likely, but, if any, more related with the causes from prior injury to the neck. Likewise, if nerve injury occurs from motor accident, ED may ensue. So, to define what cause ED, a detailed Hx, proper physical exam, and some tests are required. Enhance, see Doc for comprehensive evaluation before jumping into Dx and giving Rx; be patient...

Go see your doctor: Although severe pain may interfere with ones ability to achieve an erection, chronic pain by itself does not typically cause that. If you have spinal cord compression causing neck pain, it's possible to have ED along with other neurological deficits. Medications used to treat neck pain (narcotics, antidepressants, anticonvulsants) commonly used to treat pain may also contribute to ED.

Depends on the cause: Neck pain has many cases. the only causes that causes ED and pain are stress and depression, cord compression, low fat diet, and diabetes in your case. To find the causes need to see PCP and get proper diagnosis and tests.

Usually not.: Unless you had a severe enough injury to your neck or significant disc or arthritic conditions that you have nerve deficits from the neck down, there is little chance for correlation. But, Pain alone can be a disruption in concentration during intimacy. If the neck pain is that bad, seek medical attention for it. Otherwise time to talk to your PCP or Urologist to find out why ED continues.