Does myofascial pain syndrome cause swelling? such as my arms and legs, and does it cause muscle weakness?

No swelling: Muscles may feel swollen but not appear to actually swell. The pain sometimes feels like weakness.

MyofascialPainSyndr.: The myofascial pain syndrome causes muscle pain that can be quite severe and limiting. Usually the pain is in a single muscle, involving a single region of the body, and usually it affects just one side of the body. It is does not typically cause swelling but if a person sits for extended periods of time, fluid can accumulate the lower legs. Weakness of affected muscles may result from the pain.

Mostly no: If it does you need to be evaluated for something else in addtion to the myofascial pain syndrome. Wide spread myofascial pain can occur without swelling or weakness, but painc an limit motion and muscle use and this may be the explanation for that. With the evaluation you will be tested for additional reasons beside myofascial pain for this symptoms.