First of all, you should undergo one blood test
for beta-HCG to confirm/ exclude pregnancy at the earliest.
In exclusion of pregnancy, other reasons are ovarian cyst
(most common with above features), hormonal imbalance, stress/anxiety, thyroid problem, weight gain/ extreme loss, irregular eating habits, psychological factor etc.
Need to investigate properly to pin point the diagnosis by USG lower abdomen, complete hormone assay, thyroid profile, blood sugar & prolactin
level, blood testosterone level
etc. Consult with your gynecologist for proper guidance. You may need to take hormonal medication with other supportive therapy.
Avoid stress/ tension, take healthy diet with Vitamin & iron supplements
, control body wt by regular physical exercise and take sound sleep.
Be well and take care.