You are describing the symptoms of bloating and distention which are common symptoms of IBS. Muscle weakness is a perceived sensation but there is likely no actual loss of strength. Distention has actually been measured in IBSers. Over the past few years there has been a lot of research to figure out what causes these symptoms. Researchers still have little insight into the cause of bloating and distention but some research show that probiotics such as Align may relieve these symptoms in some IBSers. Here are links to some abstracts of research papers that talk about these symptoms in IBS.
Posts
Bloating & distention are common IBS symptoms
