Post Natal Bleeding

Hi guys, I was wondering if anyone had a similar experience? I had my baby 7 wks ago & I stopped bleeding at around 3 wks postpartum. Well the other day I noticed a few drops of fresh red blood on my knickers & I thought AF was back... So I put on a pad & then when I checked an hr later there was nothing... Not a drop of blood what so ever. During this time I had cramps & really felt the same as a would do during a period. Anyway it's now been a couple days & I haven't experienced any further bleeding nor have I had any cramping. I am due to see the Dr for my 6 wk check in a few days so I will ask then but for now does anyone know what this could possibly be? I have been cramping for a few wks now so was expecting AF soon even though I am exclusively breastfeeding I felt it was on it's way. I did have sex at 5 wks postpartum & I wouldn't mind if I was pregnant again but I'm worried it might be an infection. Also I had a pretty straight forward delivery & had no stitches or tears thank God.