What would cause my eye to twitch for a week straight ?

Blepharospasm: Is an involutary twiching of the eye lids. It could be due to muscle fatigue (the charlie horse of the eyelid), stress. If bothersome, painful, or socially embarrasing sometimes doctor may try botox. Most of the time it goes away spontaneuously (it may take days to weeks, rarely months).

Also adrenalin: Agree with dr i. Stress, tiredness and caffeine or energy drinks can put your pedal to the metal and rev your engines, kicking out adrenalin. This can make you shake (like stage fright) or even certain muscle twitches like eye tics. Good luck.