I am sorry you are so tired. I think, given your history, it could be anything. Please see your doctor. Best wishes.
I don't know what your creatine level should be at, but I do know what creatine does. It stores ATP which is what every living thing uses for energy. What the human body uses to make ATP for the creatine to store is a single sure called D-Ribose. As we age we loose the ability to create this sugar and it just isn't available in foods. You can buy it though. I have been using one under the Solgar label for the last 6 months or so. I have also been taking something called NADH. The A in the NADH is the A in ATP that your body makes out of D-Ribose for your creatine to store. Go to wikipedia and check out ADP, cAMP, AMP, ATP, NAD, NADH, NADP and FADH. Also you might want to check your pH levels. The way the electron transport chain works is that the intermembrane space has a lower pH than the center or matrix of the cell and the difference in acid or pH levels is what makes the electrons flow back and forth, making all your cells batteries. Charge them up!