Talk to Gynecologist on Primolute N

my endomitrium lining was thick on 18th day and was having a spotting and i had been prescribed primolute N one tab per day (starting from 5th day of menses) , there was a spotting until i stopped taking it and menses came back. and on 5th day again i started primolute but on 8th day i went to my gynaecologist, she performed u/s and found lining is thin and asked me to stop taking primolute.now after 2 days of stopping medication, i have bleeding like menses, can you please advise what is the cause. my gynae is not reachable.