when we were flying between a thick cloud base below and a thick base above I suddenly felt scared, I started sweating and felt like I wanted to get out the aircraft.
You probably had an episode of situational anxiety. At this point, saying that you are 'afraid to fly' may be incorrect. But if you face the situation similar to the one that generated the anxiety the first time round, and your response remains the same, then probably we are beginning to look at 'fear of flying'.
Consulting a psychologist is a good idea, but if I were you, I would rather approach someone who also has some understanding of aviation as well, lest your genuine reaction is termed as an 'irrational' fear of heights.
Dr David R Jones (COL, MC, USAF (ret) is an acclaimed authority on psychological (and psychopathological) aspects of aviation. One of his articles is about how a
pilot evolves in his aviation career (unfortunately this link is to the abstract, and so also I must say that this article is written with single cockpit combat pilots in mind, but applies as well to all those learning to fly).
hope it helps :-)