ALS patients do suffer Gas and Bloating if their stool motion is not controlled properly.
I have been giving 25 ml of Movicol Liquid with 50 ml of warm water every night for softening the stool
For immediate Gas and Bloating you may try
Gaia Herbs for Gas and Bloating or
Providac Capsules for Gas and Bloating
Also you may want to contact a doctor to check if there is any other issues.