I tend to overanalyze things here, and take a different approach than most to altered mental status but here goes:
Altered, confused with slurred speech and asymmetrical mouth
Can result from a 7th cranial nerve damage, OR upper motor neuron damage in the cortex associated with motor tone
10 and 12th cranial nerve damage possible as well
History of multiple drug use. Uses OxyContin, no idea how many taken today and can't find the bottle. Pupils 2mm, reactive
Generally a 3rd cranial nerve abnormality ruled out, and the fact pupils are not pinpoint lessens the certainty that opioids are the root cause
took excedrin and pain meds
Possibly a delirium super imposed on top of whatever else is going on, depending on whatever else she took with the Oxy, due to CYP450 drug metabolism and interactions. Oxy and Excedrin are both partially metabolized by CYP2D6
Slow, languid twisting motions of her arms and legs
Were the movements in any way purposeful? Were pain and deep tendon reflexes intact? She could be in transition to decorticate, and then decerebrate disinhibition.
What was her breathing like? Any signs of degeneration into Cheyne-Stokes respirations? Were Babinski sign present? Sign of Hoffman?
Reported to have stumbled against a door at approx 1500, some slight abrasions around her left eye. Facial bones intact, no crepitus or pain on palp
See Natasha Henstridge as a prime example of how a knock to the head in just the perfect way can kill someone, after the person is seemingly fine since the trauma.
So, you have a deficit at possibly the level of cranial nerve 7 (pons) and/or 10 and 12 (medulla), symmetrical extremity motor abnormality, possibly affecting both corticospinal and cortico-thalamic tracts.
All this would seem to point to an increase in intracranial pressure, which presses the brain downward on the midbrain, pons, and medulla. This downward pressure affects motor tone and movement bilaterally, and ultimately if untreated, can affect the respiratory centers (re Cheyne-Stokes) Just enough asymmetrical pressure on the side ipsilateral to the 7th cranial nerve deficit is enough for a lower facial palsy.
There are very, very few other things that can affect the motor system bilaterally, including CVA. You'd have to have a near complete blockage of the basilar or vertebral artery, or profuse bleeding into the pontine cisterns.