I don't know if it's implantation?

I haven't had a period yet for this month, but was supposed to have came on the 17th. My last cycle was December 17th-26th. I've been spotting all day for three days straight. I've had signs of cramping and sore breasts and everything. Everytime I wipe I see blood, but it's pink and red, very light. Nothing doesn't appear on my pad, it only shows up when I wipe. I took a pregnancy test a week ago but it was negative, should I take another? Is this a sign of implantation?