Girls, hello, January 25th was my first period day, in February there …

Girls, hello, January 25th was my first period day, in February there was a delay, on February 26th I took a test and it was positive, on March 2nd I booked an ultrasound appointment before that date all tests were positive, the second strip was brighter or darker each time, the ultrasound showed a yellow body 16mm and endometrium 16mm. The doctor scheduled another one next week, the same day started brown discharge, today is March 7th and there's no yellow body or endometrium 6mm, the tests on March 3rd showed two strips. Today it started bleeding like a period after the ultrasound. What could this be? Has anyone ever encountered something