What Causes Scanty Menstrual Period Along With Vomiting?

Well my me and my girlfriend had sex for the first time we were both virgins, and her period isnt a full period she just has brown? i think the menstrual fluid or whatever it is, and then just a little blood, and for the past 3 days she has been throwing up she said its like mucus kinda? and its sorta yellow, but its just a lot of it, she also detailed it like spitup from a baby thats been eating yellowish orange baby food...and im really just nervous for her, if you have any ideas on the possibilities it could be please let me know.