Actually, if you go with problem to psychiatrist.... they will most likely slap some label on you... because it's thought, you go there, because you see it as problem.

When you say "I don't like people" to bartender, they may agree that people suck. Shrink will not go all philosophical with you. Same with "I think of death". You discuss it with priest... you get one answer, spiritual one. Shrink? They will most likely provide you an answer that is diagnostic. Friends may be freaked out or engage in the death talk.

as the "negative thinking" link... only in some cultures death is consider OMG-negative. IN some, it's perfectly normal.

I am not saying dwell on it, but... I don't think that pathologizing will help. For me the thought that I am not forever is actually quite liberating. And it leads me to trying "for real" and trying to make something of the life. Trying to make a mark maybe.