24m muscle twitch in arm for a while. worried could be als or something. blood tests urine ana test and so on all norm frustrated with no answers?

Fasciculations: Twitching or vibrations under the skin are likely caused by fasciculations. Fasciculations are fine twitchings of the muscle fibres under the skin. This is usually most obvious when the muscle is at rest. It can be completely benign and not significant except as a nuisance. It is made worse by fatigue, caffeine, or a combination of both. See your doctor or a neurologist for a proper evaluation.

Muscle twitching: Twitching is experience by almost every human and it is almost always is benign. Muscle twitching without pain may be associated with changes in the Alpha motor neuron causing "fasciculations";. If associated with weakness the concern would be als. Can have that evaluated with ncs/emg. Diseases of the muscle: infectious, inflammatory, medication induced or hereditary may also cause symptoms.