I am on paxil--could this cause me to feel un steady on my feet, especially when I am walking on uneven ground. Walking on solid base is never a problem.
Without seeing one of these twitches or personally examining you, I can't make an accurate diagnosis. However, from your description, it sounds like you may be experiencing what's called muscle fasciculations. These are twitches that result from spontaneous firing of your muscle units. You should be able to see and feel them with your hand. And they can certainly be more pronounced with use or exercise. If you have no other symptoms with it, then it's probably benign and you shouldn't worry about it. However, if this is associated with weakness or other serious neurological problems it could be a sign of amyotrophic lateral sclerosis or lou gehrig's disease. An EMG should be able to pick these up if they are frequent enough as well as a neurologist. You may consider a repeat EMG down the road if this persists or gets worse.
Another possiblity is myoclonus which is an involuntary jerk of an area of the body. A fasciculation is much more subtle than this and does not move a whole limb as myoclonus can. A hiccup is an example of a myoclonic movement of the diaphragm. Myoclonus can arise in the setting of brain oxygen deprivation - a serious injury, or seizures. Talk to your doctor about these possiblities as they have examined you and should be able to confirm or refute these diagnoses. Glad that your workup so far is normal. Good luck to you.