The only thing for a cold sensation I can think of is acid reflux. When you get heart burn it feels crazy and can give anxiety (hence the rapid heart rate). You can remedy acid reflux (gerd, or heart burn, throat burn or whatever you want to call it) by getting some digestive enzymes (try something like Source Natural s Daily Digestive Enzymes) at a local vitamin store (or try vitacost.com) and it ll give her enough digestive juices to help grind up her food better. Also food intolerances will cause problems too. I discovered a food intolerance to wheat, milk and peanuts. But you have to write down how you feel after you eat something and try eliminating it for awhile and see how it goes. You can ask a doctor for an Elisa test (for food allergies) but it doesn t tell us much. A food elimination/rotation diet is much better plus it can t hurt. A sharp knife like feeling is definitely heart burn from what I ve felt or heard about. Make sure you write down when these things occur, what time and how long (dates) and what she had to eat earlier. Pizza is a biggie on heart burn. Hot dogs, anything with bad fats in it. Bread if she is intolerant to wheat and so on. I would throw in a thyroid (TSH) test for hyper or hypothyroidism. So many symptoms stem from those diseases (difficulty breathing, rapid heart rate, digestion issuges and so on)...that it should be warranted just to rule it out. And if it keeps happening see the doc. But sometimes I do believe we have to be our own detectives. My dd has a friend that was ill on and off for a couple years and saw 11 doctors (hello, aren t they supposed to be intelligent beings?) but no, they couldn t figure out anything. Finally they figured out she has a gluten-allergy.