What Causes Severe Left Sided Abdominal Discomfort?

I often get this uneasy, intense feeling in my left lower abdomen (similar to the feeling when you ride a roller coaster or drop a steep hill, but not exactly this) I get this feeling when I m either in an uncomfortable situation or I get it with movement sometimes, like driving. For example, I am driving and a car next to me is driving at the same speed, if I look over and see them I either have to speed up or slow down bc I get this intense feeling in my lower left abdomen. What do you think is causing this problem? And what could I do to stop it? I am taking my first flight in a month and a half and really fear that I will have this feeling and not be able to handle the flight. Sometimes I feel like my mind is getting overwhelmed by what is going on, but I do not get it all the time. It has happened when driving, walking, playing racing games, but most of the time it has to do with movement. It happens the most while driving, but it does not happen all the time.