I went in for my weekly OB appt and had absolutely no signs of going into labor....this was on a tuesday. The OB thought I'd go past my delivery date, but I went into labor on that Friday. There's no real way of telling...sometimes you have clear obvious signs and other times your don't. So without a crystal ball, it's hard to tell, babies will come when they're ready. Hang in there. Maybe diarrhea is a sign, but then again you could have eaten something bad. Look for bigger unquestionable signs like contractions that come at regular intervals or your water breaking.
Some women do experience flu like symptoms in early labor.