squeeky wheel?

I have a 98 Jimmy 4x2. When I am moving, whether it be idling down the street or 60mph on country roads, it makes this high pitched squeeking noise. It stops when I push on the brakes, but other wise it never stops. It started 2 days ago and has just gotten louder gradually. I thought maybe it was a stuck caliper, but it's not pulling in any direction when I brake. So wheel bearing maybe? I'm out of town and don't have any of my tools on me...any suggestions as to what it could be? Anybody?

It's time to change your brake pads and don't wait very long or the rotors will be damaged too$$$
How long? Depends on how long it's been squealing and your particular application of braking effort.