My mom had this a couple months ago, she also took weeks to recover. I found the following from the internet but dont know whether it is helpful cause my mom hadnt followed this.
Dear Juliemay,
My mum about 72 yrs. , she had the same case with your father. After consulted 3 times and change better .One chinese doctor is famous to deal with this case, you can try - Mr. Kam Wai Man in Quarry Bay , HK . Tel - 25640966