I self diagnose most things. I have an auto immune disorder. Went to the doc and told her what I thought it was. She comes back and says yes.
I recently went with a heart condition and told her what I thought it was. On the second visit she says...I think you’re right.
There is such a wealth of info on the net it is pretty easy to self diagnose now.
But it can take quite a while, depending on how unusual the disease is. The doctor only has about 10 minutes to diagnose. The patient has the additional advantage of knowing his symptoms inside and out.