Woke up with a headache behind my left eye today.
Pretty sure it's from tension/sore muscles as my left arm/shoulder ache as well as other parts of my body...so I'm guessing I either slept tense...or I was so tense that when I relaxed as I slept I ended up sore because my muscles were so tense.
In either case...I woke up with a headache that has so far not gone away. 
Tried tylenol and advil this morning along with some mountain dew. Currently trying to keep heat on it and eat more substantial meals today because I've been basically just snacking all week due to working evening shifts. 
We'll see if it helps or not.