Vet nurse here - your vet will 100% be able to help your dog. There are a huge range of options available for arthritic dogs now, from anti-inflammatory pain relief through to monthly antibody injections. I’ve just started my own 11 year old dog on some of them myself!
Everything a vet would prescribe is prescription strength and not over the counter. The only over the counter pain relief you could safely give a dog is paracetamol and that doesn’t have the anti-inflammatory properties to help with arthritis.
As
@Former_Antelopee helpfully suggested, you can request written prescriptions for medication if your dog goes onto meds long term
Not had any experience of CBD oil in my own pets but I’ve spoken to plenty of clients who’ve used it and said they can see an improvement. If your dog is noticeably stiff, I’d probably recommend using this alongside medication though