Protein Powder Side Effects?

My story:

Been a constant Gym-Goer , 4-5 days a week, plus running 2-3 days a week for 4 years now. 35M. Have been taking protein powder periodically post work out over the year, ( Optimum Nutrition, Gold Standard, Vanilla Ice Cream flavor).

In January, really focused on gym and took creatine and protein powder every day for about a month straight. While the gains were great, started getting Vertigo symptoms and stomach issues, thought it was the creatine but stopped both and after 2 weeks the symptoms went away.

Now in August, started taking the protein powder again (same brand and flavor but bought new 2.5KG Tub of it), and started getting the same dizziness, light-headedness, as well as bouts of anxiety and depression, something i had not really felt before.

The timeline of these symptoms started at same time as protein powder so after taking it everyday for 3 weeks, ( in the morning for breakfast on empty stomach), and the symptoms getting worse i made the connection that it must be the protein so I stopped.

Its now been 4 weeks of no protein powder, but still have the symptoms of light-headedness, dizziness, and like a weird head fullness feeling ( like a rubber band around my head). As well as anxiety/depression. and ringing in the ears. Sometimes like a rubber band tight around my head.

Went to the doctor and got blood tests, urine tests, and ECG and all came back normal.

Was hoping after a month of no protein powder it would have gone way so now am second guessing if this is the cause, but nothing else has really changed around this time. (Water softener broke , so water has more calcium but that cant be it right?!)

Anyways, looking for advice or if anyone else had this experience with either protein powder ( or the artificial sweeteners it caused). Or any recommendations on what I should do to resolve these symptoms.