Hello mam, thanks for trusting health care magic.
Your condition is known as anorexia nervosa
. The periods problem faced by you will be solved once your weight stabilises but you need to know the reason behind such drastic weight loss
It can be just a change in lifestyle or some grave disease affecting your body
In case you have further questions you can consult me on health care magic forum and i will be happy to help
Take care and wish you all the best.
Dr Manisha Jain.