My sister is complaining of a pain behind belly button, numbness in her vulva and then pleasure during sex and this is a cont pattern. what to do ?

What 2 do? Encourage: ..her to see a doctor. Her gynecologist is a reasonable first step to check for physical abnormalities. Lack of pleasure with sex can be caused by life stress, fatigue, neurologic problems such as MS, some medications, depression, marital conflict...the list is long. Only a skilled, attentive physician can sort all this out. Best wishes to both of you! Dr. Anne