Is this anxiety? Depression?

It sounds like your anxiety is a symptom of your depression. Sometimes just taking to someone may help. Try a psychologist because they dont prescribe med's. It does and will get better. I went to a Therapist and it has helped me so much.

Well this is all caused more than likely by your limbic system you are experiencing something that occurs in most people when they feel down try changing your environment or having a big day of nothing but fun and if this continues seek help from a professional as for the heart thing im no doctor so i have no clue

Go back to your gp and tell them exactly what your symptoms are and then ask the doctor to give you a leaflet on understanding and coping with whaat u have, I find it better to understand what it is and then I knw its normal for me x gud luck

Could be both I have anxiety and depression , you didn't give much detail for me to conclude on anything but good luck