Whinning sound comming from the rear??

[Rescue]

As I took off with my 4runner it started to make a loud whinning soung comming from the rear passenger side. I removed the drum, nothing. Could it be my wheel bearing seizing up? Ive replaced the other side about a month ago and it didn't make that kind of noise like now. I hope it's not the pinion bearing? but the noise is comming from the right side so I don't think it the pinion...

Edit: I removed the drive shaft and the noise is almost unhearable! could it be dry gears? I guess Ill check the oil level