About six months ago I started to gain weight, i have never been overweight (5ft 4in tall and 105lbs) and 50+ years old . Around the same time my menstrual cycle changed , with bleeding very heavy and lasting over 3weeks spoting the fourth gone by the fifth week. Also have major pain, heavy cloting and foul smelling. since this began I have gained 45 lbs.
You can make an appointment with your doctor to help you with regard to the heavy periods and to ensure that you are not anaemic.
Eat a healthy balanced diet with wholemeal bread etc. and cut out all junk food and fizzy drinks. I found this did help.
You can also buy Vitamins over the counter for people on the "change".
Best wishes.