I think there is something definitely going on. Nearly everyone I know is feeling off (including myself), suddenly developing chronic fatigue and vertigo.
By something going on you mean a virus? It is well known stress can cause strange symptoms and illnesses, and make you feel "off." The majority of the world has been bombarded by lockdowns, 24/7 death tolls, threats of unemployment. It doesn't take much to put 2 and 2 together.
Also I think the whole talk of "long covid" is giving people fatigue and long term issues subconsciously. I know people that have been tested negative for covid multiple times, never had a positive test, that are convinced they have long covid, I.e fatigue. Depression itself can cause fatigue. It would be very unusual (unless you were making bank) to be a little depressed at the moment.