As you sit there moaning from the ache in your back, you start wishing it would just spill out of you like your stomach contents did. Anything to relieve the horrendous build-up of pressure. You're about to get your wish, sort of.
A loud snap echoes through the room from your lower back, rattling your spine and making you yelp like a dog that's been shot. Another loud snap makes it feel like your tailbone is getting evicted--a hard lump forms and stretches your skin just over your butt crack. After two or three painful cracks, it no longer feels like a single bone. The ache in your back builds up to a new crescendo, then partially relieves itself out your rear end by forcing a string of new bones down into your new lump. You try to catch your breath again, but the short length of bony flesh that feels like it's trying to your ass surges with another build-up of pain and then cracks loudly and multiplies into a hairless tail that wraps itself around between your legs toward your chest, reaching almost near to your face in your curled-up position. Your hands instinctively reach for it like a mother reaching for her newborn, desperate to make contact with this new flesh and bone you've forced out from within your own being. Each hand races the other to explore as much of your new appendage as possible, rattling your brain with the sensation of your own hands reaching parts of yourself they've never had access to before.
Your tail starts to grow long brown and gray hairs while you're clutching at it, but your fading back pain is soon replaced by your hands and feet starting to cramp up. You put one hand out in front of you while still clinging desperately to your new tail with the other. You see the the underside of your fingertips starting to turn black along with part of your palms. Your cuticles start to burn, forcing out your fingernails (which drop to the floor with little clicks) before rapidly producing a new batch of keratin in a very different shape. The black hooks that are taking shape look formidabble, and the similar set of claws on your other hand soon starts dicking into the skin of your tail, forcing you to adjust your grip. A few minutes ago, you'd have been thrilled to see this: natural weapons to grace the savage body of the wild beast you'd idealized. As it is, you're so exhausted and disoriented from previous changes that all you can do is stare blankly.
Your upper arm clutches in to bring your elbows inwards toward your chest, and your fingers fingers start to shrink before your eyes even as your hand stretches long and thin. The hand that was still holding your tail is now pawing at it, and finally just waving up and down in front of you beside the other one. You wince as a surge of growth goes through your feet, stretching them out into the thin hindlimbs of an animal, shrinking your original legs to turn your ankles into bestial hocks. You kick your new feet and legs, working out the soreness but also admiring the power within them. The sprints you'll be able to take would put any human athlete to shame.
The last sensation of change is little more than a ringing in your ears, at least at first. The sounds around you get louder and crisper from the changes inside your ears. This process continues when a strange folding feeling overtakes both earlobes, making them feel empty and swollen. The image of wide, tall, pointy cupped coyote ears enters your mind as you try to visualize this (hopefully) final change. A muscle jerks somewhere near the base of your new ears, and the sounds from behind you get louder, while others get quieter. You shift these muscles around some more and find sound sources getting easier to pinpoint, swiveling your ears around until their as clear as possible. Your left panting as the pangs of change seemingly dissipate.
You uncurl yourself and lie flat on your belly, stretching your front paws in front of you, relaxing some tense muscles a little bit as you do so. Your empty belly rumbles, and you'd do anything for something to eat, but most of your aches seem to be wearing off to your relief. You actually feel kind of nice in your new form, with your shaggy fur blowing in the air conditioning and rubbing against hard floor. Your tail even wags a little, startling you for a second. You gradually raise yourself to your four paws and look over your coyote body with some awe, once again hoping you've made the right decision. At least it's over. Part of you feels very accomplished to have made it through all that. You wonder what exactly the humans have in store for you next.