His scales are growing together??

Hey hey! First post hope im going this right. I'm sure everyone on here gets a TON of questions but honestly I've looked forever and this is my last resort before taking him to a vet.

So I got my lil dude, Tash, this past August. Currently he's about a year old and is doing awesome in all aspects except this one. He's extremely tolerant and docile, I feed him by hand, he enjoys head rubs, and even comes out of his hide to say hello (and ask to come out of course) to me when I walk in the room.

Anyways, a couple months ago I noticed a small patch of scales that looked... Weird and really wrinkly. It was on his lower back maybe 1X2inches. "eh it'll come off with his next shed" it never did. Today it's pretty much the whole lower half of his back. And he's had about 3 sheds through this, all of which have been super clear with no issues.

Of course these questions will be asked so I'll try to answer what I can anticipate.
-His humidity is perfect, right around 80% at all times
-He eats great with no issues, he gets one almost full gown mouse a week
-His heat is perfect too, mid 90s
-They don't hurt him at all when I touch him
-I use coconut fiber substrate
-He drinks water a good amount
-He poops and pees every 2 meals, it looks normal and doesn't smell like anything at all

The only think I can think of that might be causing it is his hide is getting small for him, he has to curl up pretty tight but he does fit in it. I am upgrading tanks this weekend with bigger hides.

http://i.imgur.com/dyc0Fc4.jpg
His whole body, you can see the scales toward his butt look wrinkly. I also think hes a tad chubby. (picture is from a week ish ago)

http://i.imgur.com/2YKMaYo.jpg
You can see his scales are a much different wrinkly texture on his butt end. (picture from a week ago too)

http://i.imgur.com/ZqwF10c.jpg
When I first noticed it. (picture from a few months ago)

Watch that temp, mid 90s is too high, your hot spot really should be about 90 max-at the surface under the substrate (I'm assuming heat mat?) and check with a temp gun directly. How are you checking it now and is there a thermostat controlling your heat source? How damp is it in that cage? 80% humidity is a tad high too, it's ok if there's good airflow and no condensation building up but could be an issue.

Like postal said, temps and humidity both sound a bit high. What's the temperature on the cool end (ambient) and how are you regulating it?

In the first two pics I didn't notice anything weird with his scales, but the third pic does look a bit concerning. Wrinkles where the snake bends/folds is normal on a white snake (2nd pic), but I'm really not sure what's going on in that 3rd one.

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This is a 100 % speculation but it looks like he was exposed to something too hot like a RHP or light. Kinda looks like a sunburn on a snake, How are you heating the enclosure ?

Are they like that right after he eats? Hard to see on my phone but I have a lot of white snakes and they'll get marks like that after they've eaten from whatever rat juice gets on them and dries. Does it wipe off?

Lower the temps and humidity, ~80 cool end ~90 hot end and ~60% humidity is perfect. I agree with Ba11er, looks like some sort of blister (from what I'm not sure). You said he's had 3 sheds with this, how big was the affected area when you first noticed it and how much has it grown since then?

also as others have mentioned, it would be good to know what the heat source is and how it's regulated (if it's regulated)