Bests & Worsts Reviews from Amazon

I had such high hopes for this pillow as I had stalked them for quite a while trying to decide if I should get one. Before ordering, I stacked books on my bed and did the measurements carefully to make sure I got the right size. I got the 6" and received it yesterday. I let it expand for several hours before going to bed. I took a sleep aid and looked forward to a really great night of sleep. This morning I woke up with the worst crick in my neck that I have had in years. What the heck. This pillow just flattens out under my head. I felt like I would have slept better with a stack of books. Does it get firmer over time or what? Do I have an unusually heavy head? I am so bummed. And now also in pain. Not sure what to do.