Can Plan b change my period ?

So about 3-4 weeks ago I took aftera wich a cheeper verano on plan b. Now my period is super irregular like I though I got it a week ago but it’s was REALLY REALLY REALLY Light like can’t even fill up a light tampon half way and it also had some like brown (old) blood. It was like that for a week. Then today in the middle of class I felt like I was bleeding and when I check I had a normalize amount of blood but I though my period had ended Bc the light bleeding had stopped but now it’s back to being super night and a little bit of brown (old) blood. Could this be caused by the emergency contraceptive ???

(I’m also on a new diet which changes each week but I’m not eating any new foods so)