Hi again just wondering I have a pounding heartbeat can that come from a dust mite allergy or is it anxiety thanks?

Palpitations. Anxiety, rather than allergy, would explain your pounding heartbeat. However, your primary care provider will examine you and have a better idea.
Hart rate. An elevated heart rate can surely be de to anxiety but it can also be due to an abnormal cardiac rhythm and should be evaluated by a cardiologist to make sure it is nothing serious. This is not an allergy.