When you are in these situations, try and focus your attention on your breathing. 4 second inhale, hold it in 3 seconds, exhale 4 seconds ..2sec pause. This will (a) quiet your mind (b) relax your body which has tensed up from the anxiety.

Since this is anxiety you are dealing with you are probably breathing shallow and that contributes to loss of focus, and certainly makes anxiety worse.

S.E.E.
Sleep, Exercise, Eat Healthy