Suddenly irregular periods?

Hey,

So I had my period from August 10th to August 16th.

Then I spent nine days in Sweden with the Boy Scouts. Although I ate just as much there as I do here, strangely enough, I didn't have to go to the bathroom once.

Yesterday I arrived home and noticed that I was bleeding down there again.

My mother said it had something to do with the fact that I hadn't eaten enough in Sweden because I didn't have to "empty my bowels" there.

I have no idea what's going on with my body since I was actually eating just as much or even more than I did at home.

Is this normal? My mother doesn't want to take me to the gynecologist.