In the last two months I been gaining weight, mostly in my mid-section. Right after my periods Ive been getting real sick. When went to the doctor she said I had the flu. my body was aching, headaches.But, Ive been having lower mid-abdomen pain as well. Even cramping along with nausea  and it always start a few days after my period ends.As well as my period been irregular. Im 24 and 57.
Irregular periods need evaluation. Weight gain could be due to irregular periods. To know the cause I would suggest you to do a thyroid function test, serum prolactin. Also do an ultrasound abdomen to rule out gynecological causes of irregular periods.