No period

Hello! My last period was November 25th and I was expecting my next one around December 23-24 because my cycle is usually around 29-30 days long. I haven’t gotten it yet and it’s the 25th and I know there is no chance of me being pregnant. For the past few days I have had severe cramps with no period. I was looking up what might be causing this and I actually just got on adhd medicine about 2 months ago and have lost around 25 pounds in the past two months. I read weight loss can make you loose your period. In this case does this relate to me because I am having cramps but I don’t know I’m just confused. As a women I like to have my period to know my body is doing what it is supposed to do and when it’s not doing it right it makes me worried. Any ideas?