I have had some success with homeopathic remedies. There are several different headache/pain/migraine/sciatica/back pain remedies that might help you.
For my stiff and very painful neck the remedy that has helped me the most is from Newton (http://www.newtonlabs.net) and is Sciatica-Back care. This remedy says nothing about stiff necks but it has worked the best for me. You will probably have to experiment, consider the migraine remedies because a lot of them work for occipital headaches which tend to migrate into a sore/stiff neck.
Still, what helped me the most was CHANGING MY PILLOW. You may have to experiment with this, but I got a cheapo pillow at Wal-Mart (a Serta pillow that claimed to be cooler) and that has helped most of all of the things I've tried.

I find a couple of magnesium (and a good supply of vit D if you use sunscreen normally), helps as  more than the ibuprofen and tylenol I used to take regularly.And I have to avoid cold temperatures/wind.  i also totally swear by the exercises my physio has given me. A few weeks ago I messed up my knee, which made me walk lopsided, but I thought I was managing. That threw my back muscles into a really bad spasm. i woke up one morning and could barely shuffle, from back pain, let alone walk. I couldn't do anything. Physio got it partly fixed later that day, but it started to seize up again in spite of exercsises. Next morning I was seized up again, doing exercises desperately, somewhat better by afternoon. Next morning it was pretty good! But I had some heavy work that absolutely had to be done, back was good. Till I was almost finished. Wham, back seized again. More exercises, but this time it started staying right longer. I'm still being a bit cautious, but at least I'm getting some physical work done. Even though it seems like the exercises don't work immediately, without them I would have been immobilized and got nothing done . And it really makes me pissed when I can't function. Surprisingly, since I've been doing the lower back exercises, my shoulders and neck are better too. So, it's only taken me too many years to figure all this out. But still it's progress! Some of the pain that I thought was chronic joint/hip arthritis, was actually really tight tendons and muscles. Arthritis doesn't get suddenly really bad, and then magically cured, then bad again. That's muscles seizing and releasing. But if I don't get them released they just seize chronically for days or weeks.