In female there is rhythmic contraction of uterus
,uterine tube,vagina and sarrounding muscle following orgasm.This may cause slight pain in lower abdomen but nothing bothersome.pain following masturbation
may be due to various causes such as direct minor trauma during this act,getting infection in that area.Female urethra
is very close to vagina.So it is very vulnerable to direct trauma and contracting an infection.Lack of proper hygiene during this act also perpetuate this condition.Better to give it up.There
is a religious prohibition also.If you find it intractable,consult a doctor and get a course of antibiotic as appropriate.