Do you mean brain fog? Do you have any dizziness as well? You may have developed SSCD if that's the case - I have it.
Go read up on Semi Superior Canal Dehiscence. It can cause brain fog, dizziness, balance issues, loss of taste, tinnitus and pulsatile tinnitus, etc. If that sounds like you it's an easy test - CT scan - that's often overlooked by doctors so you just need to ask to be tested for it. That could potentially be another condition known as Microvascular Compression Syndrome - again go read up on it. And it's easy to test for as well but you have to ask for it as most doctors - beside a Neurologist and Neurotologist - aren't aware of SSCD and MCS.
Good luck.