Twitch in let shoulder

Hi, welcome to the ehealth forum and I am glad to help you.
There is a condition called benign fasciculation syndrome which results in intermittent muscle twitching. It is labelled benign because it does not progress to any other disorder. If, in addition to the twitching, sufferers often experience pain, paraesthesias, generalized fatigue, exercise intolerance, globus sensations and/or muscle cramping, then the diagnosis of neuromyotonia (Isaacs syndrome) can be made instead of BFS. Regarding the possibility of ALS, if your neurologic examination is entirely normal, it is unlikely. Other things which can cause muscle twitches include stress and occasionally electrolyte disturbances.
Unlike ALS, BFS symptoms are usually present when the muscle is at rest, and are not accompanied by severe muscle weakness.
Some degree of control of the fasciculations in BFS may be achieved with the same medication used to treat essential tremor (beta-blockers and anti-seizure drugs). However, often the most effective approach to treatment is to treat any accompanying anxiety. No drugs, supplements, or other treatments have been found that completely control the symptoms.
Hope this helps. Take care.
Note: This answer is not intended as and does not substitute for medical advice - the information presented is for patient education only. Please see your personal physician for further evaluation of your individual case.