Front bearing growl

Had my front bearings replaced on 2005 prius about 1 month ago as the right side bearing was making all the usuall noises of a bad bearing...After about 3 weeks the right side again started to make a low humming noise but not quite the same as the original problem bearing, this time there was no change in noise on wide sweeping turns like there was with the original problem...Took it back to the mechanic and had him ride with me and he immediatly diagnosed that the bearing had failed again, even though the noise was differant....He replaced the bearing on Friday, I drove it home with no apparent noises, put maybe 100 miles on it Saturday and noticed again a low hum starting on the right side...Now here on Sunday it is a very loud hum/growl with some shimmey coming from that side...I'm guessing it's not a bearing problem, haven't talked to the mechanic yet but does anyone have any suggestions on what else it might be in that area.....Thanks

 

Thanks for the reply.....The one and only reply, which is surprising......You hit it right on the head though.....Just heard back from my mechanic and thats what he said he is replacing, the bearing in the trans....I'm guessing it went bad after I had the initial front bearing replaced....You had asked about a fluid replacment and that had been done when I had the bearings done the first time...As a person who admittadly doesn't know a whole heck of alot about that part of a vehicle you have to wonder if all he did the first time contributed to the trans bearing failure----or was it all just bad luck.....I do not know.