Being irregular is a common occurance if you've changed your eating habits significantly in the last month or so. Even a healthy change can throw off your hormones. It will straighten itself out in all likelyhood.
Also, you don't say how old you are but if you're in your 40's, things have a tendency to get a little wonky.
In the meantime, I'm with everyone else. Don't stress too much, drink lot's of water and be sure to eat a balance diet even if it's a little less for the time being.
Hope