Suggest Remedies For Pain Caused Before My Heavy Periods

Hello,I am 49 and have very heavy periods, like if i was giving birth, every month,It has started after having my second child and I have been to the doctor and have been given valium, but about ten days before my periods I get very moody and snap at every one, which has caused a lot of problems, what can I do about the pain and the bad temper?