has your period ever changed drastically?

So I'm not on birth control and not having sex. My period usually comes every 32-34 days and it's been regular for years. This month (I think) it started around 10 days early and it's very light. I usually have cramps so bad I stay home sick but this time it's been pretty much pain free. I thought I must have ovulated late and this was just ovulation spotting but I kind of think it just came really early... I started a pretty intense diet last week and have been working out more but this has been strange. Just wondering!