Headlight problem and 12 volt outlet blown fuse

I am having the headlight problem on my 2006 prius (and have seen thousands of posts about it). The drivers side goes in and out and has done so for 6 months. But now the passenger side is doing the same and the 12 volt outlet fuse has blown. There are 133000 miles on it (nothing done to the vehicle except oil changes and new tires) Replacement bulbs from eBay are on the way. I have replaced the fuse and its ok now. I don't know if they are unrelated or if this a battery issue. Any thoughts?