Is it just the eyelid drooping? If that's the only part of your face you can see that is affected, probably start off at your eye doctor to rule out eye infection. Wear your glasses until then (if you usually wear contacts) until you know it's not infected.
If the eye doc can't rule anything out, ask for a referral to a neurologist. I don't want to freak you out either, but they'd probably give you a CT or MRI, so be prepared for that.
Good luck, I hope you find that nothing is serious
Type 1 Diabetic. Controlling blood sugar through primal life.
Maintain A1c of 6.0 or lower
More dietary fat, less carbs, moderate protein
LHT and sprint as per PB fitness