Muscle twitching is a fundamental aspect of your nervous system. According to “Beyond Biofeedback” by Elmer Green, there is a measurable pulse that has been identified as single neuron firing. This means that basically your nervous system is maintaining constant contact with your muscles. This is normal.
The problem, according to Green, is when the brain “loses touch” with the muscles in question. This could be a response to stress (such as constantly tensing a muscle group to respond to poor posture). This can lead to spasms, illness, and is suspected in cases of cerebral palsy. He even cites work where patients were able to partially recover from cerebral palsy by doing awareness training with the effected muscle groups.
That said, your case is somewhere in the middle. But I believe you can gain ground by doing the following:
1) Make sure your diet is sufficiently nutritious, including trace minerals, sodium, and potassium.
2) Make sure you are exercising on a regular basis. Regular exercise strengthens and tones muscles which is likely to keep them from atrophying and/or spasming at unwanted times.
3) Take time each day for relaxation. Relaxation is important to return striate (involuntary) muscles to a normal state after periods of stress. Tension in striate muscles over long periods of time may lead to twitching, pain, and disability.
4) Make sure you are breathing. Failure to breathe can cause all kinds of problems. It seems obvious, but a lot of people would be surprised how often they hold their breath or breathe more shallowly than they should. Breathing patterns are learned, so they can be changed through conscious effort.
5) Practice progressive relaxation. This is a technique where you lay down and relax your whole body one part at a time. You do this through deep breathing and concentrating on each part in succession. You tense the specific muscle groups in question, hold the tension, and then release. You mentally instruct the muscles to relax as you exhale and release the tension. The tension generates awareness of the muscles. The relaxation “resets” them.
I’m no doctor, but if you pay attention to all of these things I would bet you have fewer complaints. If you see no improvement, it’s probably best to see a doctor.
Good luck.