What does waking in the night with a pain going up my back and into my neck/throat mean? It goes after walking around for about 20 minutes.

Maybe reflux. "heartburn" can be experienced very differently in different people. The first concern for any pain like you describe is the heart. See your doctor. If its not heart trouble i'd try an antacid (e.g. Tums (calcium carbonate) or something similar) the next time it happens, and if it provides fast relief, you have your answer. I had a similar problem and have found it was my esophagus causing chest tightness.
Angina maybe. When the heart is working harder such as long time walking, angina accurs and some patients do not belong to the typical angnia, chest tightness performance, toothache, and abdominal discomfort, neck/throat pain also a common symptom.