I would start by saying that I have severe anxiety which I found xanax completely cured and that was after taking anti-depressants which I didn't believe I needed to begin w/and they made me suicidal and homocidal and I've never been either. I'm a very very happy person but I have bad panick attacks and social anxiety that is often prompted by thinking I'm dying. I've had all kinds of things (in my head) like heart attacks, cancer, strokes, blood clots, tumors in the brain, EVERYTHING I ever saw or read about. I get the numbness and tingling and I also get a rapid heart beat, sweating and my vision is blurred along w/dizziness. The tight muscles I've never heard of or the muscle spasms. I'm not trying to scare you at all and I realize most anxiety is caused by the person thinking there is something more wrong than is but you should go to your doctor to be sure. The one thing i found to educate myself was that we all have different symptoms associated w/anxiety. Not too many get the dizziness I have but that doesn't mean there's anything wrong and that took yrs for me to get over. Good Luck
these could be axiety symptoms because i get pretty much the same sensations your talking about. But at the same time if it persists maby you should see a doctor. Especially if your on birth control and/or smoke, because blood clots are possible.