Brief Answer:
Should be evaluated

Detailed Answer:
I read your question carefully and I understand your concern.

Generally a stroke has more manifestations than the facial asymmetry. There is also some degree of weakness or numbness in the body particularly in the upper limb on the same side with the facial weakness. So I wouldn't consider it very likely.

However while not likely, there are cases of minor stroke which may have very few signs. So if you are sure this facial asymmetry has appeared only today (there are people who have some facial asymmetry) then an evaluation is warranted even at the emergency room and if confirmed that it is a central nerve palsy (as opposed to the peripheral benign Bell's palsy) imaging is required. You are at a uncommonly young age to have a stroke but still the association with the neck pain may indicate a cervical artery dissection which is a common cause of stroke in the young.
Pain in the back of the ear is a feature of Bell's palsy as well though, so do not want you to be alarmed, but should be seen to differentiate between a peripheral and central nerve palsy (usually easy to do through observation of some maneuvers with the facial muscles - in Bell's palsy muscles of the forehead and eye are involved as opposed to cases with brain lesions where they are spared).

I remain at your disposal for other questions.

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