I want to thank you all for your quick replies. I kept checking back throughout the day.

I took a trip the pet store today to pick up supplies, and the wonderful breeder of my healthy female (who happens to work there) was in. He asked me to bring the little guy in.

Amazing breeder guy looked him over completely, checked him out for me and sexed him - definitely a male.

Anyways, he said he is certainly not older than a year. (I also was thinking he was six months) I sent a text to the lady I took him from, as well as an email, regarding his age - but she has yet to respond. He said that my boy is definitely dehydrated, recommended lukewarm baths for the next few weeks and for his size, fuzzy rats. Needs to up his feedings to once per week, so I will make sure that happens. Hoping after a few feeds he is able to move up to pups and so on. He said to come in with any other help I may need, or send him a message.

So, good news. After a nice lukewarm bath tonight, he drank a bit of the water and seems more energetic. I've put him into a smaller tank and I can already see a difference. He is curious and exploring a bit. Yesterday, he had no interest in doing anything except hiding.

Awesome breeder guy is confident I will be able to get this little guy healthy and beefy in no time, its nice to have that reassurance! Thank you again for your advice. I have ordered 2 Hydrofarm thermostats so they should be here next week. Until then, I am home almost all day so I will keep close watch on the temps inside the tanks.