Thema: Feeling a feeling?

I am diagnosed schizoid personality disorder and have generally been described as emotionless or emotionally flat.
Some time ago I had an experience that was both annoying and enlightening. I had a strong recurring impression that something was wrong. So much so that each time I would have to stop and examine my surroundings and life to see if I could find a reason for this feeling. Not being able to find a reason, I would put it aside and carry on. After a while it stopped. Talking to someone about it then doing some reading, it seems to me that this was the physical manifestations of an anxiety or panic attack. I imagine that particular physical sensations tend to accompany particular feelings. I know this sounds incredibly stupid but this is something I have not considered before. Does anyone know where i might find clear information about this or could you share any experiences you have had. I feel like the blind man that is trying to describe an elephant when all he has to examine is it's tail.