This sounds kinda strange, but it can be something as simple as gas buildup. Gas buildup can mimic a backache as well as a heart attack. If you have any tums or pepsid, something of that nature, take a few, wait a few hours and take a few more. Most of the over the counter remedies for gas are calcium based and about as natural and non-harming as you can get. If it doesn't go away from taking them several times, theory is blown and on to another one.

Also, have you changed the way you're sleeping at all? That could lead to that kind of issues, and it's also spring. Allergies can affect any part of your body with inflammation and discomfort, not just your nose. Just a few thoughts.