Thanks for using the forum. I am happy to address your questions, and my answer will be based on the information you provided here. Please make sure you recognize that this forum is for educational purposes only, and it does not substitute for a formal office visit with your doctor.
Without the ability to examine your husband and obtain a history, I can not tell you what the exact cause of his symptoms is. However I will try to provide you with some useful information.
There are many potential causes to your husband's muscle twitch, some are serious, such as ALS as you mention, others are more benign. A benign, unworrisome cause of muscle twitches is called benign fasciculation syndrome, is a condition in which there are involuntary twitches of various muscle groups, most commonly the legs but also the face, arms, eyes, and tongue. If the diagnosis is confirmed and other causes are excluded, it can be safely said that the likelihood of progression or occurrence of a serious neurologic condition is low.
However in general, when fasciculations occur in the setting of associated symptoms such as progressive loss of sensation, tingling or numbness, weakness, trouble swallowing, slurred speech, and other symptoms, the cause may be due to a peripheral nervous system problem. The location of the problem could be the anterior horn cells, the area where the nerves that supply motor innervation to our body comes from. These are the cells that give off the nerves that allow us to voluntarily contract our muscles. The diseases that might affect the anterior horn cells include ALS (also called Lou Gherig's disease), a condition called spinal muscular atrophy, polio-like viruses, west nile virus, and other infections. Another nervous system problem, neuropathy, may also lead to fasciculations. There will again be associated weakness or sensory changes. There are several causes of neuropathy.
Some metabolic causes of generalized muscle twitches with slurred speech include systemic problems such as infections, liver problems, thyroid disorders etc. several of which are treatable/reversible.
It sounds like your husband is on the right track with evaluation by a neurologist. A test called EMG/NCS which tests how nerves conduct electricity and how the muscles respond to stimulation is often helpful in making a diagnosis when someone presents with muscle twitches.
Thank you for this opportunity to answer your questions, I hope you find the information I have provided useful, good luck.
What about a Chiropactor?