1. Get yourself to a sports doc or competent chiropractor and make sure this isn't the start of something serious. Stop running until you get evaluated.
2. Make sure your shoes aren't worn out. If they are a year or more old, or the outsole patterns in the heel/toe areas have significant wear, get a new pair.
3. Do *not* take ibuprofen before you run! It can: a) irritate your stomach something awful; b) allow you to further aggravate your injury because it won't hurt as much and you'll be tempted to run farther/harder; and c) really, really screw up your kidneys if you get dehydrated.
Good luck.