I've had to live with this condition for most of my adult life. First group of attacks was when I was 19, they weren't correctly diagnosed till I was in my mid forties. I wasted years of my life being mis-diagnosed because it is a fairly rare condition (well under 1% of the population) and extremely difficult to treat effectively. Over the years I was prescribed everything on the market for migraines none of which had any effect. I was put on lithium, methysergide, ended up with an addiction to opiates, had electric shock treatment, one quack even told me I was imagining things and sent me to a psychiatrist. Thought I was going nuts, felt suicidal with the pain. I finally got to see a Professor at Birmingham University Hospital who diagnosed it immediately at the first appointment, he was the only Doctor I'd seen in 25 years who had any knowledge of it. Got it under control now but it still flares up from time to time. I've had to keep a supply of oxygen at home for the past 20 years and otherwise manage it with calcium channel blockers and a very occasional shot of morphine.

Having suffered so long with it doesn't exactly inspire me with any level of confidence in the NHS so in answer to the Op. yes I do have a tendency to self diagnose before I go anywhere near a doctor's surgery. Can you blame me?

https://en.wikipedia.org/wiki/Cluster_headache