[Faboosh]

I don't know exactly about his worsening aggression, but I can say that we did sort of what your trainer told you to do and it worked for us beautifully.

We were told (on YT actually) that when Billi bites, make a loud squeal and pull our hand away for a few seconds. Then start playing again, and when she bites do it again. It's basically the same thing her litter mates would be doing to her if/when she bit them. It took a couple weeks for Billi to really get it, but she did and she has never bitten any of us since. I will add that we got her at 8 weeks, and by about 12-13 weeks, she stopped completely. She'd get a little better, then she'd regress, then she'd get better and then stop altogether.

Part of it is like what Taylor mentioned, having these pups at such a young age- it's up to us to them teach them what their mom and litter mates would be teaching them up until about 12 weeks of age. He could be getting more aggressive temporarily and then back down, I don't know. But it's definitely worth talking to a new trainer and continuing to squeal and pull away in the meantime.