Brief Answer:
Benign facial synkinesis

Detailed Answer:
Hello and welcome to Healthcaremagic.

What you describe seems like a case of what is called facial synkinesis, an involuntary muscle movement following a voluntary muscle movement. Both eye closure muscles as well as the muscles around your lip are under the control of the same nerve, the facial nerve. The nerve is composed of many nerve fibers corresponding to its different facial muscle areas. At times there can be a miswiring leading to the same fibers commanding the eye muscles as well as a muscle around the mouth, hence the impulse to the eye muscle is spread to the muscle around the lip.
It can be without a cause, a benign born feature, or can happen due to damage to facial nerve, otherwise called Bell palsy. If you're sure it's been present only from 3 days, facial nerve damage may be your case. If you've noticed no facial asymmetry or other symptoms it is a very mild case which you haven't noticed at all and this is only a remnant. When isolated, without other symptoms, the cause most often remains unknown, a virus is one possible origin.
Anyway, it represents no threatening condition and most cases gradually recover completely by their own. At times when there is visible nerve damage with facial asymmetry corticosteroids and antivirals are used during the first days, but if you have no visible paralysis and asymmetry I wouldn't opt for any treatment.

I hope to have been of help.

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