Help, dehydration?

[northerndragon]

Hi, I got a baby BRB on October 3. He's my first snake and after working out some things I did wrong in the first few days (keeping him in a tank and not giving him enough cover) everything is going pretty well except for one thing, he appears to be skinny and very dehydrated. He's been like that since I got him, with some crazy wrinkly skin, and he actually has stuck shed on him from the store I got him from, a locally owned reptile store that I assumed bred them and knew what they were doing.

I'm keeping him in a 72 quart locking plastic bin, humidity is at 100%, temperatures are 85 on the warm side and room temperature (65-75 varying on time of day) on the cool side. Temps and humidity monitored through digital gauges with probes.
I don't know when he last shed. I don't think he's in shed, his belly is white, eyes clear, scale colors bright. Unsure of his weight, I don't have a scale yet.
He has two big water bowls big enough for him to soak, one on each side, that I refill/replace every other day. 3 hides and lots of foliage for cover. Cypress mulch with a bit of sphagnum moss on top as substrate.
He seems pretty healthy, very active at night and hides all day (although he hides in weird places and doesn't tend to use his actual hides as much as the foliage), though he's not once been defensive or nippy with me.

The store told me he last ate with them on September 25 and that he was eating pinkies once a week. I didn't successfully feed him until October 22 with a f/t pinkie, and I gave him a fuzzy on October 25, I next plan on feeding him November 1. I know that's a bit odd but the pinkie was way too small and since he went a long time without food I wanted him to have something else for substance, I don't plan on doing it again but if that messed things up please let me know. The reason I couldn't get him to eat for a while was that he's incredibly shy and I was using videos of other snake feedings for reference of how to do it, and the only thing that worked with him was holding the mouse completely still for about half an hour until he came up to it and started to "nibble" on it, and lightly rubbing it against his mouth. He also has not pooped yet.

Even though his stuck shed mostly came off just from being in high humidity with me, he still appears very dehydrated and wrinkly. I know it can't be due to the water/humidity since most of the stuck shed came off, but I don't know what else I can do.

I've been told it could be due to not having enough to eat, which does make sense, but I'm not sure how long it takes for the water from the food to reach him. I am having a few doubts over what the store told me about him eating, he was a lot smaller than his siblings with him (at the time I assumed they were just females and naturally larger, even though all of them are unsexed), but that could be something else, I really don't know.

Will this go away once he's digested his food and pooped? Should I take him to the vet about this? What can I do? Thanks for the help, I really appreciate it.