Anxiety is an absolutely reasonable explanation. I've experienced the very same symptoms you've mentioned, and yes, I was diagnosed with anxiety disorder. Sometimes I would suffer a panic attack if I were terribly upset or stressed, and sometimes they would just come on out of the blue. I know how awful they can be.
I was on a low-dose of Xanax for a while, which really helped, but I weaned myself off them long ago. I've had no panic attacks since stopping the meds; I've felt them "coming on" several times, but I've been able to "talk myself" out of them.
You may want to do a search on panic attacks/anxiety disorder. You will probably find that you have experienced many of the symptoms. If you're lucky, you'll be able to recognize anxiety for what it is and keep your symptoms from progressing without the use of medication.
Best of luck to you!