My left eye has been twitching for nearly a month. should i be concerned?

Eyelid twitcing: Do you mean eyelid twitching? This is sometimes called blepharospasm. By itself, it is benign. When it occurs for several months, and it is very bothersome, people sometimes use medication for this. Normally it is left alone, and it resolves. http://www.neurocuro.com/blepharospasm-eyelid-twitch/

Myokymia: Eyelid twitching, or myokymia, is a benign but annoying condition. Reducing your stress and reducing caffeine intake make help.