Hiya,
i am really sorry to hear that your robo is ill
I am also sorry to say that it is probably the fluffy bedding which has caused the problem!! You really need to remove it straight away - it is very dangerous! If accidentally ingested, the fluffy bedding cannot be digested and will cause blockages which will make your hamster very ill and will usually end in death! Another bad thing is that it can get trapped around limbs and is very dangerous.
I am not sure if this is exaclty what has happened to your robo, but i would mention it to the vets and see what he says. I am not sure that an operation could be performed on such a small animal to remove a blockage, but see what he says.
I hope your robos gets better soon.
ETA: just wanted to say that 5g of weight is such a lot of weight for such a small animal to lose! If he doesnt show any improvement by tonight i would get him back to the vets straight away tomorrow.
Keep us posted.
Tammy x