Strange Garter Snake Behavior

So I was walking down a trail by my house today and I stumbled upon a 2 1/2 foot garter snake. Of course the first thing I did was run after it and pick it up because... you know... that's what normal people do. :P Anyways, when I looked closely at it I could tell it definitely had some minor injuries so I took it home to hoping I could help it out. It was especially more wounded on the tail and back third of the body. I set up an enclosure for it, and when I took it out I set her down just to see if it could slither properly, which it did, but when I went to pick it back up it froze and began to thrash the back third of its body. I kept the front 2/3s of its body completely still in a straight line. I was like "What the heck!" This happened several times, and I began to realize that the vast majority of its injuries were on the back third of the body and tail.

I know that some animals have fake faces or eyes to fool predators, and some snakes use their tails as lures for small prey, but this looks like it is trying to get the predator to attack its tail area instead of its head on purpose. I have never heard of this before. Has anyone else heard about or seen behavior like this? Most people don't associate snakes with being intelligent but this proves that snakes can learn certain behaviors to survive.

My first thought is for the snake: you say it's injured on the back third of it's body, so you should not be handling it when that causes it to panic, thrash & further injure
that part of it's body, IF you're trying to help it survive, & stress doesn't help it either. I'm not sure about garter snakes doing caudal luring, but their usual defense is to
expel musk, so maybe it was just having trouble doing that. Another thing, many snakes (other than rattlesnakes) vibrate their tails under duress...it has no apparent
connection to caudal luring, & some speculate they gain protection by imitating rattlesnakes, but snakes are deaf & it's extremely unlikely that is a deliberate "learned"
survival technique...it's just something they do. Anyway, I hope he'll be alright...let him REST!

I was handling him as little as possible. I just wanted to make sure that he could slither properly, in case there was some sort of serious internal damage. I was just gently trying to pick him back up to put him in his cage when he started doing it. He musked me pretty good when I first picked him up so I don't think he was having trouble there. This was definitely not rattlesnake mimicry. I will try to get a video in a few days once he has settled in and calmed down.