Syncope or Seizure?

Looking for thoughts on your instincts about my experiences. I'm putting my main query first, so that you don't have to read my background. I occassionally have fainting spells. Previously, these occurred 5x a day and any time while walking. Now, they very occassionally occur and usually in the same week. I've only fallen once in the last 18. I get tingly arms, then my vision goes black and I see bright slights. If braced (leaning forwards on a wall), I stay in that position rather than losing muscle tension. If not, I fall down and my eyes roll back into my head. Does this sound more like fainting or seizure? Background: In my teens, I had both these and sudden spells where I would sometimes stay awake but sometimes not and my knees would collapse under me so that I fell down. Unfortunately, I counted them together and am not sure how many of each, only that sometimes the sudden spells would happen two or three times in a row. At the time I have severe dissociation, so it was put down to first postual drop and then anxiety so sudden I didn't realise it's onset. My recent one was attributed to postural drop with the explanation that BP tests are inclusion not exclusion. (Fair enough.) I was later diagnosed with ASD and ADHD. Medical testing for ritalin safety showed normal ECG, normal BP, normal blood tests. I've never had a medical EEG but had one as part of my psychology degree. I am dubious as to its value in any respects. It wasn't possible to run analysis on because I kept having spike waveforms where I shouldn't. I got told off for fidgeting several times until a demonstrator sat in with me and saw I wasn't. They tried more fluid on the electrodes, etc, but gave it up as a loss while insisting that the equipment was working. I also have short periods where my hearing (garbled) or vision (quite cloud blocking vision) doesn't work properly and short periods where I get stuck and can't move... followed by longer periods where I can't speak properly but can sometimes sign... but this could well be ASD shutdown or ADHD processing difficulties. I also have moderate hearing loss and the hearing thing is not because of that. Cause undetermined. MRI normal. Every few months, I get a single jerk usually in my right shoulder that occurs several times over a few days. Usually happens at/near home... which makes me think not a seizure? WAIS IQ test (for ADHD) shows working memory/processing difficulties (average or below average compared to 99th percentile verbal scales).