How Can One Differentiate Between Miscarriage And Implantation Bleeding?

I have a 26-day cycle with a 12-day luteal phase and my last period was either on 4/26/11 or on 5/22/11 when I had a light flow. I am early pregnant and a week ago I pulled a shopping cart of groceries up one step and noticed that my breasts were not hurting anymore later that day and the day before yesterday what would have normally been the day before my expected period, a clear, thin, water-like liquid spilled from my vagina after I lifted something with someone else so that it would not be very heavy and yesterday I had some bright red bleeding on and off but not the usual amount that I would have with my period.and today I have been feeling the same little twinges I have been feeling for weeks, I am more nauseous, still have sensitive, heavy breasts and the areola and nipple on each is getting darker quickly and my Montgomery's tuburcles are still prominent. Could the clear fluid and the light bleeding be a sign of a possible miscarriage or implantation bleeding? I am not feeling any pain.