Have you had your thyroid checked? I know this sounds like a very weird question but back in 2006, I was dealing with panic attacks, shortness of breath, loss of weight, rapid heartbeat and fatigue.
My doctor ordered this travel EKG thing or whatever and I had to wear it for 24 hours. It stunk, but it helped them to see if there were any abnormalities in my heart rate. It came back fine and then I went back to get blood work taken.
I started taking these herbs called Nutri Calm, which helped me relax and since it was all natural, that helped. When my herbalist checked me over, she said my adrenal glands were out of whack (that's when she offered Nutri Calm). Come to find out, she was right on my adrenal glands. My throid was like 5.2 and the dr's like it no more than 4. So, I now take Synthroid .05MG once per day. It's worth looking into.
But before any of this stuff happened, I ended up in the hospital twice for Hyperventalating. It was awful!!!! The first time I hyperventalated, my mom took me to the ER and ran in to get a nurse and I remember her saying I was hyperventalating. I swore I was having a stroke because my hands started tingling and they drew up, like I had no control. Then my lips puckered and I couldn't talk. That's why I swore I had a stroke. Finally after the nurses started demanding me to breathe, I did and I was better. But this all happened before I knew I had a thyroid issue. Both ER doctors said I was crazy. I knew something was up and good thing my doctor found out it was my thyroid. I've been on medicine now since 2006 and I'm doing better. I still don't feel as good as I once did. I think once your thyroid goes whacko on you, you still aren't the same, but the good thing is so far I've never had to change the dosage and I've had 3 kids since then too. Although I did just have blood work taken for this a few days ago so hopefully nothing has changed. I feel better too. Once on the medicine, it does take about 4-6 weeks before your body starts to notice the change in the medicine. If you do have thyroid issues, they will monitor it through bloodwork and keep monitoring it every 3 months until you hit 1 year. If you haven't changed dosage in that time, they will usually check it every 6 months and eventually every year.
Sorry for the long response. Good luck.