I would say it started happening about two years ago.
They can last about 30min-1hr
My mother gets anxiety, but certain life stresses trigger it.
When i was about 14 yr old i can remember having a similar situation, but not shortness of breathe or nausea, just crying and blurred vision.
I thought maybe fear of something, as she always needs the closet shut tight and she complains of shadows moving in her room. We keep two night lights on for her and most night she falls asleep fine, although she does get insomnia at times.