Our last Syrian wouldn't touch anything that had medicine in and would give you a black look as if saying - are you trying to poison me?
Difficult - some of them will reject anything if they think it has anything in it. If he has nearly finished the course then in future you might find something he likes that would disguise any future medicine that might be needed!
Glad he is improving a bit. Echinacea leaves can be a bit difficult to find (dried usually) and he may not eat them anyway if he's picky! Maybe just keep to the usual diet and the brazil nut is an extra
You could also try some hemp seeds - they are supposed to contain every vitamin and mineral there is so that will help with immunity too. When our last Syrian was old and needed a dietary boost I used to put those out twice a week and he licked them up out of a little baby food lid (any small container to have them separate really - or even just put them on a square of cardboard or something.
He would ignore normal seeds but liked the shelled hemp seeds which are kind of fluffy and look a bit bigger!
I got the Linwoods ones in a bag. Holland and Barratt usually have them (they are for hoomans to put on their cereals I think) and Amazon sells them too.
Even if he's allergic to hemp grass and fabric , doesn't mean he's allergic to the seeds.
https://www.amazon.co.uk/Linwoods-Sh...led+hemp+seeds
If you're a bit worried about the hemp/allergy thing though, then Linwoods also do a mix of flax seed (linseed), sunflower and pumpkin seeds, which is very nutritious and good for zinc (which is also an immune booster) and vitamins generally. And saves buying lots of different packs of seeds. I'm sure he'd like a teaspoonful of that as it has sunflower seeds in
Maybe best to be on the safe side and not use the hemp seeds.
Zinc was found to cure/lessen colds and flu in people with leukaemia (it was found accidentally). But it isn't always absorbed well as a tablet or humans could prevent colds and flu easily - but in the seeds it is naturally there. Hammies tend to only take what they need of seeds etc.
https://www.amazon.co.uk/Linwoods-Or...nwoods+linseed