What Is Causing Heavy Bleeding With Cramps In Abdomen?

Hello I am a 45 year old woman 5'7 50 kgs 2 kids- 14&17. I have been having really heavy bleeding and cramping in my lower abdomen which I do not normally experience. I have been needing to change my tampons on and off every 30 mins to an hour and was using pads in addition but now am just sticking to using pads instead. If I lie down I am somewhat better but when I stand up and walk a lot of blood comes gushing out. I now seem to be having heartburn which I never get and have a headache as well. This has been going on for the last 4 days. In addition my breasts are still very tender which normal goes away fairly quickly after my period starts. I have up until recently had very light periods lasting 3-4 days. Needless to say I am worried and am not sure if seeing a physician is in order yet as I just moved from France and all my physicians are there. Thank you for your help.