Muscle twitches as you describe seem to be more like 'myoclonic' twtiches rather than '
fasciculationsMuscle twitching'. Myoclonic twitches are fast
contractionsFetal heart and uterine contraction monitor
Fetal heart monitoring
Tension headache of a muscle that are usually irregular.
I cannot give you a formal medical opinion, as this site is purely educational, so you should followup with your doctor.
In general, myoclonic jerks are most commonly benign, and often occur on going to sleep, or waking from sleep, or when tired.
Sometimes it can be a sign of generalized forms of epilepsy - in this case the jerks usually start in the mid-teens, and there are assocaited convulsive or staring siezures by the late teen or early twenties. An EEG may be a helpful test.
Myoclonic jerks have a whole range of other causes, limiting me to be specific to your case. Examples include drug side effects (such as opiaites), and metabolic derangements
Good luck
and to clarify my early post, while the twitches or jerks or whatever are noticable and annoying, they aren't particularly violent or strong.
If you are suffering these weird symptoms, I suggest you check out the following sites:
www.medicationsense.com
www.fqvictims.org
http://health.groups.yahoo.com/group/quinolones