I would have your physician assess this especially since you have being experincing heavy periods.
Usually it's not that abnormal to have a more foul smell during your period. But there are a few reasons the odor could be more foul this month than others. The PH levels change from acidic to more alkaline and bacteria flourishes in alkaline levels which can lead to infection. If you've been trying to get pregnant and your period is very heavy this month, it could be miscarriage. And like I said, it could just be normal, or it could be some type of infection. Unfortunately there are numerous reasons this could be happening. If it persists, I would definitely get it checked out. Good luck to you and in getting pregnant in the future :)