Thank you for your question. There are many possible explanations for this symptom that you are describing, but it is important to understand the context of the symptom, meaning what else is happening. Additionally, your family history, past medical history, medications that you are taking, and many other factors need to be addressed to provide a possible explanation. That is why it is important to discuss your concern with your doctor
. Any explanation will likely focus on what makes a muscle twitch, or fire. In general, muscles have action potentials, or stored up energy that is waiting to be released when signaled to do so, which usually happens with a nerve impulse that is sent to the muscle and will often stimulate further firing. Understanding this helps to understand some of the parts where you could be having origination of the problem that you describe: either the nerve could be sending abnormal signals or the muscle could be firing without the appropriate signal. There are many things, such as fatigue and certain medications, that can affect both the action potentials and the nerves themselves and lead to certain problems similar to what you are describing. For more information about your question and a physical examination, please speak with your doctor.