What Causes Momentary Loss Of Balance?

Hi, I am a 77 yr old lady in what I consider good health...on no medications and am presently succeeding in overcoming morning anxiety! :) I went out this morning, came home (one cup of decaf and some oatmeal) started to open closet to put away my coat...when suddenly I felt like I was going to fall over...it only maybe lasted a few seconds, but scared me. Never happened before... Now I am a bit afraid it might hit me again while I am walking. Any advice?