possible hamster arthritis?

[ggsquill]

not too long ago I noticed my beloved 8 month old long haired hamster, Arlo stop using his wheel.
about 5 days ago when I took him out to play I noticed that he started losing some hair near his scent gland on the left side, but that is normal for some hamsters.
2 days ago when I took him out he was sort of limping weird in his cage but when I took him out he would walk fine and then limp and walk fine again, so I treated this as a leg injury because I didn't se anything wrong anywhere else and moved him to a 1 layer cage without his wheel or any ramps.
yesterday, he was doing about the same.
today, he is fully dragging his back left leg and his hip feels very tight. I flipped him over because I panicked and checked for any other signs of illness and found none. then I checked if his leg could still move and it just barely could. then I palpated up his leg for pain or broken bones and didn't feel anything abnormal, well except for the tightness in his hip. I compare the tightness to the feeling of a human Charlie horse btw. now during all of this he showed no signs of pain or wincing. he still walks around the cage as normal, is well hydrated, and eats as normal. the only other thing that I noticed is some slight swelling of his belly, but he is still having normal bowel movements and peeing.
after doing some extensive research, and yes, making a vet appointment, I think it is arthritis, because of the tightness. does anyone have any suggestions or can give me advice on hamsters with arthritis living a plentiful life? due to his age I also think it is genetic because I didn't not buy him from a chain pet store, but I adopted him from a local pet store 5 months ago where he was born and handled by people everyday.
I am very upset about this because I treat him like gold and he is like my child.
please give me some advice.

[souffle]

A vet visit is definitely needed to see what is going on here. Does he climb at all? It sounds more like he has fallen and damaged something either in the leg itself or in his back. Sometimes internal swelling can press on the nerves making matters worse. The hip could be dislocated. This might be why there is swelling on his abdomen.
7 months is too young for arthritis. Occasionally they may get it but not until 18months plus I would say.
Hopefully the vet will be able to find the cause. Some anti-inflammatory meds and painkillers will help but I'd advise cage rest in a smaller cage with climbing opportunities and flat surface and no wheel. Give plenty alternative enrichment like chewing sticks, cardboard to trash and sheets of kitchen roll as well a lot of attention. Let us know how he gets on at the vets and good luck