It looks like he has a crooked hips. Part of the enlarging hip bone appears to be the additional "bump" that is showing up now. Deformities like this occur from time to time in tadpoles but breeders usually cull them if they are noticed. Normally the tadpole will have a visibly crooked tail near the base and when they morph they will also have a crooked back or hips. Sometimes the froglets will do ok and just look a little odd but most of the time they will fail to thrive and die eventually. I doubt there is much you can do and in this case from what you describe and what I can see I would agree with your assessment that the frog should probably be put down.