If you are concerned that your hamster is possibly sick, look for these sighs. Eyes looking dull, ragged fur, non-shiny fur, dandruff fur, fur loss, runny nose, lumps, and bumps. There are many other symptoms too.
Other symptoms:
https://pethelpful.com/rodents/Hamster-Health
Other symptoms:
https://pethelpful.com/rodents/Hamster-Health