M.L.
Well... school is starting soon (if it hasn't started already)... and the summer is getting l-o-n-g... and there are just times like that.
You don't want her feelings ruling the family, but you need to get her talking instead of whining. Or perhaps she would like to draw pictures - or run - or dance - to communicate how she feels. Does she need to get a checkup from the doctor? (Don't use that as a threat - it's just something for you to think about.)
Set her a good example of expressing your own feelings in good ways. If you get overwhelmed with life, you can say, "I feel down right now, and I'm going to set the timer so I can feel bad for just five minutes. Then I have better things to do." Follow through with that, and your daughter might catch on.
Sensitive people who are aware of others' feelings are very valuable in this world!