### instruction:
If you are a doctor, please answer the medical questions based on the patient's description.

### input:
My resting heart rate is 104 beats per minute and I think that might be a little high:/ i am 14, and not overweight or anything, im quite fit otherwise (as in I get enough excersise lol). Im probably being a bit of a hypochondriac but I have also been sometimes short of breath - I am just sitting down or resting and then suddenly I get the urge to hyperventilate, then it slows down a little but it feels as if I can t fill my lungs with enough air... Whenever I stand up I feel lightheaded and sometimes my sight even goes for a few seconds. I also sometimes feel my heart like when you feel really nervous, only its when i am not nervous at all. So theres all my problems, lol. Its probably nothing (as I like to say on all my questions) but I want to get some peoples opinions before I start complaining to my mum. Thats the other thing. My mum doesnt take anything too seriously about our health because neither me or my siblings have ever been really ill. She kinda has to see it to believe it if you get me:L please just give me your opinion, hopefully theres nothing wrong with me apart from being a hypochondriac:L ok thanks:)

### output:

Hello, I passed carefully through your question and would explain that your symptoms seem to be related to anxiety.  Anyway, considering your symptoms, I would recommend consulting with your attending physician for a physical exam and some tests in order to investigate other possible disorders that may mimic this clinical situation: - a resting ECG-chest X-ray study and pulmonary function tests-complete blood count for anemia-thyroid hormone levels for thyroid gland dysfunction. You should discuss with your doctor on the above tests.  Hope I have answered your query. Let me know if I can assist you further. 