Hi, and welcome.
I can help you with this.
First, you need to make sure that the second period was not implantation bleeding because you are pregnant.
A pregnancy test is in order at your due date, or a blood test before that.
Otherwise, anything that disrupts your hormones can do this, hormone imbalance being the most common cause.
also: stress, weight loss or gain, too much exercise or too little, and other problems such as thyroid, liver or kidney.
So, if this is new for you, talk with your doctor and have an exam.
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