One month after Botox Injection, my left eyelid is relaxed and a bit closed!
One of the potential risks of Botox is that it can seep to other muscles, most commonly seen is the muscle that lifts the upper lid, and if this happens then the upper lid will droop. This is self limiting and will resolve.
How ever the sudden pain you had is not typical for Botox. I would advise you to see the plastic surgeon who injected the Botox and have a complete eye examination by an ophthalmologist.
Botox injected near the eyebrows, can spread to the muscle that elevates the eyelid. If this is what happened, this is self-limiting and will wear off when the Botox wears off. However, if it is significantly bothersome, there is an eyedrop that can, occasionally, partially reversed the droop. This, however, does not generally come on suddenly nor is it accompanied by any pain or even discomfort. It is conceivable, therefore, that you somehow avulsed the muscle that elevates the eyelid from its normal insertion. You did not say who injected the Botox to begin with. If this was a plastic surgeon with significant experience in eyelid surgery, return there. If not, find a plastic or ophthalmic plastic surgeon with significant experience in treating eyelid problems. This site can aid you in finding a plastic surgeon near you.