What Could Twitching And Numbness In Arms Suggest?

I've been having increasing trouble with my left arm since December. It started with a little numbness at the tip of my index finger for a while. Then I began to get occasional tingling/numbness from my hand up to about the elbow. After that frequency increased and my elbow began to start hurting fairly often. Now I'm having muscle twitching in my upper arm and my pectoral muscle. I have no idea what's going on. I plan to see a doctor within the next week but I wanted to see if I could get some idea.