If you're not going for a couple of weeks then it could be an idea to take him to the vet now - especially as he can stay in his detolf! Reason being, if she does prescribe meds (eg a week of antibiotics) you can get those over with before you go. It would be tricky and worrying to expect someone else to get antibiotics into him successfully. If they prescribe metacam as well that's less of an issue as not drastic if a dose is only partly taken or missed and tastes nice so easy to mix in with baby food. Whereas the full dose of antibiotic is important (and harder to get them to take).
Also at the same time you could ask them to clip his nails (if they need clipping!) and kill two birds with one stone. And he'll still have a good week to adjust after the vet visit with you around, before you go away.
I suspect they will probably prescribe baytril and metacam just to see if either work - which is fairly standard when they don't know what it is. Just in case it's infection or as an antiflammatory. But I may be wrong - they may just prescribe metacam or nothing at all.
I took our first hamster to have his nails clipped by the vet when he was about 2 I think - after that I did it myself but it took a LONG time - about two weeks! I'd get one nail clipped every time he was out of cage (holding them didn't work for me - just surreptitiously snipped one while he was distracted eating something). And I find it a bit tricky even now - wear two pairs of glasses so I can see them clearly and don't cut the quick!
Anyway maybe his nails don't need clipping! Yes it's an upheaval going to the vets and can stress them but he should settle again in a few days and definitely in a week I'd say. Especially if you know a good vet who is nice with him and handles him nicely.
Latterly I took to making vet visits as least stressful as possible by taking everything but the kitchen sink with me!
Hamster would be in the Ferplast Aladino. But rather than being taken out of there and plonked on a table and them not liking that, I also took a RUB box with me - about 30cm high and 50 x 40 ish. With a hemp mat in the base of it, a couple of toys and a tunnel and some food and treats to put in it.
Then I would put that on the vet table, take the hamster out of the pet carrier myself and into the rub playpen type box and let him run around in there and enjoy the treats and food. Distracts them completely from the whole clinical thing and it was actually helpful for the vet to see him in action as well and get a good view of what's what without picking him up.
Of course she did need to pick him up at some point to examine him but by then he'd chilled a bit! And went back into the taming box afterwards enjoyed that, and I didn't put him back in the pet carrier again until I was ready to leave - and did it myself.
Also in the pet carrier I use a fuzzbutts snooze cube! As a house. It just fits, on top of the substrate. All our hamsters have loved those as a cozy hide and tend to be in it when getting to the vets. So easy to get them out without them hiding at the bottom or feeling grabbed by a hand. You just lift the snooze cube out with the hamster in and put it down in the taming box and they just walk out - very civilised!
However those snooze cubes have a second exit at one corner they can get out of and fall so I close that off with a bulldog clip so there's only the one entrance. Something similar might do.
It makes the whole thing a much more pleasant and less stressful experience. I get some surprised looks carrying the taming box in and a bag with all the bits in and setting it up (only takes a few seconds) and having to say to the vet - do you mind if I just put him in here first - they just accept it.
They just sleep in the pet carrier on the car journey sometimes and I don't think that's a stress for them really - just out of cage experience! It's the homer snooze cube (the mini one - good size for syrians - not the larger ones for rats).
Fuzzbutt mini Snooze Cube fleece house for your mouse,hamster,degu,glider