Real labor or false?

Let me start by saying this is my 3rd baby. Both came naturally but the first my water broke so I knew I was in labor, and my 2nd I felt the contractions starting, but I always already scheduled to be induced that day. So I didn't time them or anything. Both kids came early, my first was 4 days and my second was 6 days early. Ok so on to what's happening right now. I'm 38w1d and I started having cramping this morning around 6. Nothing out of the ordinary but they never stopped. They were about 15-20 min apart. I got up to go to the bathroom around 7:30 and had some spotting, which I've had none of this whole pregnancy. I stayed in bed and the contractions slowly got closer together so I decided to get up and shower and get ready just in case. I went to the bathroom after my shower and this time there was more brown and pink streaked in. So I decided to start timing the contractions and they got to a point where they were anywhere between 5.5-7.5 min apart and 45 seconds to a min or so long. It went on this way for over an hour so I called the on call doc and they said it was a good idea to head in. Of course, once I got off the phone, they slowed down tremendously to about 13-15 min apart and only 30 seconds or so long. So I decided it's best to not go in right now. My question is, does anyone have experience in contractions slowing down and it still being the real thing? I was only 1cm dilated and a little over 25% effaced at my appt on Wednesday.