Unusual discharge

Hi,

I recieved my positive pregnancy tests on Tuesday (did 2 at different times of the day) then on Friday had some very small brown discharge so did another two tests and they again came back positive. However over the weekend my discharge has been very unusual, sometimes brown, sometimes nothing and other times a very light pink/brown colour. There has been no clots but worried because it is so inconsistent and it is only when I wipe. I have had no pain at all but have a a very slight dull pain in lower back and sensitive boobs. Concerned that it could be a miscarriage as the colour discharge has been 3 days now. Roughly around 5-6 weeks pregnant x