Whenever it gets to what you consider bad, I think note it down. Then maybe you can start noticing when/how often? When I am generally overcome with anxiety it tends to happen once in the day (but lasts for different lengths of time, anywhere from 10 mins to 12 hours)... but not every day.

Have you tried Mindfulness? (like on the spot meditation style thing?) I suck at dealing with anxiety most of the time anyway so can't really help :(