One of the first suspects when you have brain fog upon waking is sleep apnea which is when you stop breathing while sleeping. This can occur from once or twice a night to many times in an hour. Sleep apnea deprives your brain of oxygen for all those periods you stop breathing, which can cause brain fog among other things.

Sleep apnea can be made much worse by medications especially sleeping pills or any others that depress the CNS (central nervous system).

Sleep apnea is easily tested for, usually in your home with an overnight test.

If this sounds like you at all please be tested.
I live in Canada though so I have no idea about insurance or costs.