Anxiety takes many forms, but usually has an initial trigger like desease, stress, emotional trauma and sometimes once the initial trigger is resolved the anxiety also falls away, but often it continues and that is because the brain has developed a behavioural habit that once something happens, then react this way. So medications can be used to dull the response and this may be enough to allow the brain to learn a different behaviour, but usually it requires some degree of counselling or personal conditioning to re train the brain.
I think CBT (Cognitive Brain Therapy) is often used and there are lots of other techniques so speaking to someone and explaining when you feel the anxiety coming on, they may be able to help you identify the problem and then help you develop techniques to respond a different way.
I did some research on this for other reasons, and it comes in many forms, many people have morning anxiety and one I read about was the 6:00pm Sunday anxiety, something happened one Sunday at 6:00pm and this guy got locked into a cycle, he'd be fine all week, then he'd get to Sunday, around noon he would wonder if it was going to happen, As the afternoon would wear ion he would think about it more often, then by 6:00pm he was in a full on attack, nothing caused it, just the fear feedback loop in his brain.
Sometimes a distraction helps, stop doing what you are doing and do something else, physical preferably, another one is the challenging approach where you challenge the anxiety, literally saying "Is this all you got", that aspect deals with the fear driver.
Probably best if you talk to someone face to face.