Thanks for the question Olivia,
I have dealt with small rodents such as hamsters for the last twenty eight years, and from what you say yours does seem quite sick. I am concerned he may have a disease called wet tail.
I am so sorry I cannot suggest any home remedy, you should get him to a vet as soon as you can. At one year old he is not too old, middle aged really, your vet may prescribe some antibiotics which can easily be given orally and perhaps some fluids you can give with a small dropper to support him while the antibiotics take effect.
Here is a link with more information about wet tail : http://www.petwebsite.com/hamsters/hamster_wet_tail.htm
If I can advise you further please do not hesitate to get back in touch.
Scott Nimmo BVMS
As I cannot examine your animals my advice is given strictly on the basis that it is for your interest and education only. Please consult your vet if you have any concerns about your pet's health.