Please see this questions!

[mixtomaster]

I am a hypochondriac. I am male, 26, underweight.
Tension headaches, muscle twitching in left foot, dull back ache, neck stifness are my current symptoms.
I was diagnosed with sinus tachycardia due to anxiety. All the test including ECG, EKG, Echo, and an expensive test dont know its name but it was kinda CT scan of thoracic region, all of them went normal with no abnormal signs.
I usually dont feel palpitations but only when I check for my heart rate, my heart starts to pound.
Today when I was walking and listening to music, I started noticing a weird feeling in my body, I checked my pulse by putting a finger on my neck, my heart was pounding. I took a deep breath and the rate became slower but not normal.
Also felt a little out of breath at that time.
Here are my questions:
Q1. What makes the resting rate of the heart fast?
Q2. What causes you to be out of breath when walking or taking a little exertion? Is it normal?
Q3. My whole back muscles aches if I lie down for sometime including my neck and back of my head, also my leg and arms usually sleeps when I sit crossed leg or put my arm under my head while sleeping. Is it connected with weak circulation?
I always think that my heart is pumping harder to supply blood to all the organs of my body but there is some problem. Please explain me this. It's haunting!

[drinae]

I'm not a doctor, and your questions are probably ones that only people with medical training could answer reliably. But I'd like to provide an alternative answer which might reassure you a bit: your symptoms with your back sound somewhat similar to mine, my back is in a bad shape due to sitting in front of the computer too much and also because of tension/stress which makes it worse. In a certain position, my arm will start to go numb and my back sometimes aches if I lie on my back, but it goes away after a while. Of course you might have your back checked by a doctor or a physical therapist or someone, maybe they can tell you more. I've been doing yoga, it helps a bit. I should do more.

A few years ago, I also had weird episodes when I would suddenly have a fast heart rate out of nowhere - but since I'm still fine and haven't had any of these episodes in the last few years now, it seems to have been harmless. I read that sometimes back/neck problems can cause something like that to happen. Probably anxiety can cause it too. So if you have been checked by a doctor and nothing has been discovered, then maybe you could consider whether you might just accept that all kinds of weird symptoms can happen and it isn't necessarily anything serious.