My thoughts in the order I had them as I read your posts and saw the pictures:
83 grams?!? Surely they weighed him wrong! 83 grams is less than 3 ounces... no way! Well, possibly because of the food, but.. NO WAY! (Please check that weight again and tell me you typed it wrong, lol) Awww... tiny guy. That's the good stuff. Crap. CRAP. CRAP. CRAP!!! I want to slap someone. He doesn't look too skinny in spite of everything. Surely 83 grams was wrong. KNEE PADS!!!! I love knee pads!! And the yawn, lol. Wow! Teeth look good. He is young, 1.5 years may be about right. Someone has nice nails.
So now, in a little more depth. He looks good, in spite of his gosh-awful diet. He doesn't LOOK malnourished, so maybe he wasn't on that horrid stuff long enough to seriously affect his health. You said he's a teeth grinder. That is an indication of pain. I know you've already headed to the vet. Hopefully, he can find a cause that is easily treated. His teeth really do look good. I'm not an aging expert by any means but I would put him at about a year and a half, which is what you were told. From your comment above, I take it that he didn't appreciate the soup, lol. Really push it at him today. Once he gets hungry, hopefully he'll go ahead and eat it.
The Rescue Remedy can be applied topically. Just rub a drop on their noses or ears or foot pads, really anywhere you can get to skin rather than fur.
My internet is still down, but I'll check in again tonight.
Ok yes it was a typo lol....825 grams, still skinny but really long legs. No he did not like the soupie but did luck it, no to salmon oil today. We keep trying the soupie. Those nails are my wife Jami's.....you'll see all types of colors every 2 weeks....purple shades mostly ? Our vet said he was about 2, teeth in good shape little tarter on one side, she didn't say much about grinding though. We noticed a little cough once with us and once with the vet....wasn't concerned as she said it was more like hiss/clearly throat cause she was giving him a shot. I'll get some more teeth shots and tag Heather since she is our teeth expert. The Dr just finally got a distemper supply for ferrets. We only did rabies and she does benedryl before and we stay for 30 min to watch. She wants to give Gomez and Jax distemper shots in a month then the next one 3 weeks later. I am afraid to do it since they have been out so long but also afraid to not give it too....thoughts? I asked who made it and she said Merle or Merrill as the manufacturer. We are going to slowly introduce the 2 boys but keep them separate for sleeping till we know how they are doing. Hope your Internet gets fixed. Snowing here today, lightly but sticking.
I'm thinking 3 yrs. Clarity is 1/3. As it's been discussed in other threads, the actual age may be younger but due to nutritional gaps they're actually older than their chronological age. I've always maintained that age isn't that important other than to prepare you for possible problems. I've had ferrets who've come in who's actual age was under 2 yrs but their teeth and their bodies are much older. ciao