ABSOLUTELY do a diary. but, time is of the essence so keep it as concise as possible. something they can glance at really quickly, perhaps a list of dates/times down the left column and maybe a three word description in the right column? it's really a wonderful way to give the docs a better picture of your day to day life without their having to listen, possibly interjecting with their questions, which can make you forget what you had wanted to say, etc. when you do go to the doc, you should really only need to take about three representative/typical days to show. no need to drag in a filing cabinet with you
from the sounds of it, the pain could be down to combined issues with magnesium and vit d3. both of those are also very useful tests to have done, and you might be able to get some bloodwork done before november. once you have some lab results, you can take action.