I had 4 impacted wisdom teeth removed 6 mnts ago. One side of face now appears swollen and asymmetrical, with low muscle tone. How can I reverse this?

See oral surgeon. There may or may not be a problem. See the dentist who extracted the teeth. If the procedure was not done by an oral surgeon, seek the opinion of a board certified oral & maxillofacial surgeon.
See your Surgeon. Start by returning to the surgeon who removed your wisdom teeth. Explain your findings and see whether or not it is related to the surgery. Your own surgeon can evaluate you properly and make suggestions\recommendations.
Consultation. I don't know whether these are related. Call the Surgeon that removed your wisdom teeth for a consultation and, if necessary, treatment or referral.