This could be a possible sign of a thyroid condition, and testing for this is done with a TSH thyroid blood test.
Also, this could be a possible sign of PCOS - polycystic ovarian Syndrome - and an ultrasound can be done to look at the ovaries and the uterus.
And, then this could be a possible infection - and some swabs of the vagina should be done.
BUT this also could be that your body is adjusting - and hence your body can have a cycle like this and a normal cycle is still one that occurs every 24 to 35 days, and sometimes brown spotting can occur - which is common.
So for Now, IF you are trying to get pregnant - then just have a TSH thyroid blood test and an ultrasound to check your ovaries
a thyroid problem is very common in women - so it is easy to check and if you have a thyroid problem - it is easy to treat with medication such as Synthroid.
I wish you well
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