I notice the grouch syndrome when I have cheated (though ever so slightly) with some caffeine or too much sugar. We just can't deal with the stimulants normally.
Another possible cause could be low blood sugar. Have you ever had your blood sugar tested?
Sometimes I feel very emotional and will cry all day. But, it could also be a reaction to the medication. If it's happening frequently, I would contact your doctor. Some of the anti-depressants and anxiety meds will cause those reactions and need to be changed. Read the labels on your medication or look up side effects on the computer. I had to have one of mine changed because I was so out of control and my emotions were all over the place. I hope this helps.