Hi..my Sister Is 21yrs Old And She Had Irregular Periods

Hi..my sister is 21yrs old and she had irregular periods for last 3months. She also gained a weight of 7kgs in 2months. We went to Gynaecologist and she has done couple of tests and gave medicines. Even then my sister didn't get her periods and then doctor tested for tb and esr test gave result as ~25mm which considered to be normal. She got her periods few days back but again went for esr test today n it showed 52mm. What could be the reason in such sudden increase we are worried as we have no clue about this rate till now. Please direct us what could be done. Thanks so much!