Is 100 units (forehead) of Dysport too much? Left the office with extreme head pressure. Brain fog & ear popping 2 yrs later

The maximum duration of the effects of Dysport, Botox and Xeomin is no more than 3 or 4 months. Your ear problem is likely ear or jaw related and should be evaluated by your primary doctor primarily followed by appropriate consultations to otolaryngologist or oral surgeon if indicated. 

Dysport only works for 3-6
months so it would be unlikely that your issues with brain fog and ear popping
are from the Dysport injection. We advise you to see your primary care
physician for further evaluation.

A normal full treatment of Dysport is about 150 units. This would treat the full forehead, between the brows, and the crow's feet. So, if you got 100 units this is not an uncommon amount. Ear popping wouldn't be from Dysport - that would be from your jaw muscle most likely, which would have nothing to do with a Dysport treatment to the forehead. You should see an oral surgeon to examine your jaw. "This answer has been solicited without seeing this patient and
cannot be held as true medical advice, but only opinion. Seek in-person
treatment with a trained medical professional for appropriate care."