The answer is NO, we can't always identify them!!!
This is what makes masto so difficult sometimes, there is not always a trigger that we can identify! Here's an example:
It's hot here in Brazil - our summer while it's your winter. So, this right here is a major factor. Yet, it's been hot for a while and I know how to work with it through keeping my house cool, getting my t-shirts damp and sitting in front of fans ,etc. When you live in a tropical country you find means of dealing with the heat and staying out of the worst of it.
I was up at 8AM, not way too early, and had breakfast with my husband and then he left and I began to do odds and ends around the house and got on the computer. I'd taken my meds with breakfast and all was going fine. I had no issues. I prepared lunch for my son and I - a light lunch due to the heat, and everything was fine when I sat back down at my computer.
Suddenly WHAM the wave of malaise hit me and I began to feel just awful without notice. I went up to my bathroom feeling the tell tale cramps but nausea also came with it, something that rarely happens. I began feeling tremendously weak and confused as to what was happening and I was also flushing! After I came out of the bathroom I didn't even think antihistamines, all I could think was BED! I was exhausted and feeling COLD and I had to wrap myself up in a warm blanket and crash out! I slept for 3 full hours a heavy sleep and I probably could have kept going if I hadn't gotten to sweating from being so hot! This is a sign that my BP is coming back up! I'd gone into shock!
After I got up I took another antihistamine for I was still dopey and couldn't answer my son's questions! But now I'm feeling much, much better and almost back to normal except for feeling tired.
What was my trigger? I've not a clue! It wasn't food, it wasn't lack of sleep. Certainly not stress! The heat is the only thing I can think of, but I wasn't feeling as warm them as I am feeling right now!
All I can say is, there are times when we just don't have an obvious trigger and sometimes there really isn't one. Sometimes it's a combination of things and the last drop is what overflows the bucket, but then, since I'm an autoimmune case, perhaps it was just the fact that I am allergic to me may have been it.
Hard to figure out at times!
Sometimes it's a game of "GUESS THE TRIGGER" !