Most likely from my experience it is from anxiety.. I get like this way more than I’d like myself to so I know how worrying it can be.. with anxiety we over think and dwell.. but just practice on relaxing techniques and drinking lots of water!! Always get as much rest as your body and mind needs

Make sure your eating well too!

that feeling can last an uncomfortable amount of time. My suggestion is to just step back and distract yourself. Listen to music, drink plenty of fluids, try not to dwell on anything worrying you, this feeling will pass just give yourself some time to quiet your mind and heal

It can be. When I feel anxious I get dizzy and can get migraines and the fatigue can be there too. I know it's hard not to worry while it's going on. What helps me is I think that quote "this too shall pass" or I go walk outside.

It may be the worst feeling but usually what helps me is resting