I've had usual auras that lasted for hours. I've also had symptoms for a day or 2 before I get a full blown aura or migraine, such as nausea, vomiting, feeling spacy, etc.
Many years ago, with my first migrainous episode, I got what I now know is an aura, then I started losing my vision. I also got total black spots around my eyes. It got so that I had like tunnel vision. It was all black to the sides, and up and down. I could only see things in a small area directly in front of me. I can't remember how long it lasted, but it wasn't that long. However, it did scare me. I had no insurance, but did go see an opthalmologist, as I thought I had something wrong with my eyes. They did their tests and everything checked out okay...nothing wrong with my eyes. However, the doc told me then that it was possible I might have had a migraine without headache. They suggested that I should see a neurologist or neuro ophthalmologist. But I just couldn't afford it, so I never went. I've had some more episodes over the years where I got black spots and I usually get ear ringing at the same time.
I certainly have no idea what really happened as I couldn't have it thoroughly checked out...but if you can afford it or have insurance, I think you probably should see a neurologist and maybe get an MRI just to be sure. After a lot of researching on my own, it seems that some migraines/strokes can have similar symptoms. But to reassure you...my first episode occured approximately 18 years ago and I'm still here and still have my vision, etc. So hopefully it is nothing serious.