Please stand by for detailed answer.
I have sent your question to Danielle as she is our best hamster expert and I know she can help. She will answer as soon as she comes on line. However, Your hammie is acting pretty sick so he is either not feeling well or older. If you are using pine or cedar bedding that could affect him so you should change to care fresh which is paper.
i am a firm believer in where there is life - there is hope so get some plain pedialyte in the baby dept of any store and give he little guy one cc - very slowly - over an hour. Hammies live between 2 to three years so I do not know if he is at the end of his life or just stressed.
Here is a site I hope will help.
Please let me know what happens and if you need anything at all. I will try my best to help in any way possible.
Please try yo hurry as I do not know how long Marvin can last. Wrap him in a towel, if necessary.
Plaese let me know what happens.