What causes twitching on top of upper lip,appears after i strain lips,like pursing,eating,smiling a lot,any upper lip straining, can lasts for several minutes...it's happening for 9 days now?it feels like lot of movement but it's almost invisible.

Need to examine: It is not feasible to provide a meaningful opinion without additional history, physical examination and may be some tests. Just in case it is due to an electrolyte imbalance, take orange or other fruit juices for a couple of weeks and if that does not resolve the matter it would be prudent to see your doctor. Wish you good health!