Sporadic anorexia with no apparent cause: what's going on?

[Magician]

When Aladdin's friend first died, I had to syringe feed him for 1-2 days, then his appetite returned. Since then, he's had 3-4 more periods of temporary anorexia where he has required syringe feeding for a day or so, but never any longer. There is no apparent cause for this, although this time round (I've just put him back in his cage after syringe feeding, as he turned down food last night and did not eat overnight, but he is now happily munching grass!) it seems to have occurred at roughly the same time his little companion plush toy was taken out for washing. I haven't put it back in yet though.
Can anyone shed any light on this? He's lost some weight (was 900 and something grams, is now 800 and something) but is still producing good droppings and continues to drink well during this periods of anorexia.
When his friend, Lenny, was ill, Aladdin accompanied him to the vets and had a general MOT: his teeth were good and he was reported to be in good health. At about 5 and a half years old he does sometimes suffer from impactions but these do not affect his ability to defecate and I simply remove them to prevent any discomfort.

 

[Mother Hubbard]

So is your boy on his own now? did I read the correctly?

 

[Magician]

So is your boy on his own now? did I read the correctly?

Yes, he is by himself, as I haven't found any suitable guinea pigs to bond with him yet and am unsure about trying to bonding if he is potentially unwell.

 

[Livia Rabideau]

He might be sad. Missing his friend. I would take him to the vet for a check up. If he gets the all clear, try to find him a friend. Hoping he is well!