We know the following were all yes questions....
He shot himself and the shot was from his own hand.
He had gone to the city to visit a doctor.
He traveled alone.
He has a disease.
The disease is not fatal.
He brought the gun from home.
He normally carried the gun with him.
He had no prior plans of shooting himself.
He shot himself on the way home after being in the city.
This one is a step lower than the guy with the arm in the box. You have to ask yourself why the questions you asked were relevant to the story. If they are not, they are answered with a no. So each of the pieces above, being answered with a yes, all play into it. Think outside the box.... :-D