How concerned should i be for sudden onset of unilateral pulsatile tinnitus after months of noticeable mild cognitive impairment accompanied by migraine-like headache and vertigo precipitated by motion? ed, urgent care, or earliest primary care?

With those symptoms a visit of your family doctor is warranted and I think a brain imaging test such as CT scan or MRI should be ordered.

If the migraine headache is debilitating despite home treatment, or the vertigo is severe enough to limit mobility and increase risk for falls, please get seen in person immediately. It could be possible to get a same outpatient clinic visit, otherwise an urgent care could be an alternative if it has a CT machine. The ER would unlikely be able to order a brain MRI