Hello guys. I have a husky/german shepard mix that I got at the pound about two months ago (my first dog

), however, he has a few bad habits. Unsure of how old he is, but he is less than two years old.
One of those seems to be trying to bite his rear paws. Tries biting either paw, doesn't seem to have a preference. When he does this he gets agitated, snarls and flails his body and limbs around trying to bite (I think nibble would be a better word) his rear paws.
If I try to grab his paw he will angrily try to get at my hand so he can continue to get at his paw. He never bites to harm, it's more like a nibble. I guess he's trying to say "Let go, damnit!"
When he does this, sometimes I will pet him and speak to him softly..to mixed results. Sometimes works, sometimes doesn't.
It isn't that frequent, but he does do it a few times a day. I just visually inspected both rear paws and they look normal, no obvious wounds.
Should I be very concerned?
He also sometimes tries to chase his tail, but this is very infrequent.
All advise, insights, etc welcome. Thanks
Edit: Sorry if I didn't post in the correct subforum, wasn't sure if this should be in training, new dog owner or general
And a pic

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