Almost every day at a random time i would hear my heart beat in my ear. should i be concerned? i do have an anxiety disorder.

Hard to guess: That is the curse of having health anxiety. Normal bodily sensations and abnormal bodily sensations all are perceived as signs of illness... making it very difficult for either the patient or the doctor to tell when the patient is actually sick (other than suffering the sickness of health anxiety). A teen can teach himself which of his sounds, his aches, his sniffles, etc., are normal sensations.

Tinnitus: What you hear is not uncommon. Your main artery which carries blood to your brain goes thru your inner ear. You are basically hearing your pulse. Some people are more sensitive to that sound than others.