Pain Management for Elderly Cat after Tooth Extractions

Hello,

My elderly cat (aprox. 13-15 yrs) had 6 teeth removed 3 days ago. He now has none left, except for the tiny incisors in the very front.
He is currently on 'Buprenorphine' Post-Op Analgesic three times per day, but I would like to stop the heavy pain meds after another day and move to a homeopathic remedy, such as Arnica (?).
He gets one 30c dose of Nux Vom. per day to help with the aftereffects of the anesthesia and possible ill effects of the pain meds. I normally try to prevent chemical/allopathic pharmaceuticals whenever possible, but didn't want to play games with the pain management due to severe nature of this particular surgery.
He ate well the night after surgery and the two days after. Today he barely touched his food before I gave him the buprenorphine, which tells me he's still in a lot of pain. However, after the dose of pain meds, he seemed ill and I gave him a dose of 30c Nux Vom. He now is laying down stretched out long, where before he was crouched up in meat loaf position.

If Arnica (or another remedy) can replace the pain meds, what potency should I give and how often? He weighs 14lbs and is a fairly large cat in size, but not fat. I would also like to help him speed up his recovery.

I normally crush pellets between two spoons and drop the powder into his mouth, but since I currently can't handle his snout properly after the surgery, could I dissolve the pellets in a syringe with a bit of water and squirt it into his mouth?

Thanks in advance for any advice and suggestions.