For the last 4 days I have had a strange light period. The first day it was a brown colour and not very much only showing occasionally when I wipe then the next day it went to a light pink blood again only sometimes when I wipe it is now back to brown and still nothing coming onto my pad. I have been having unprotected sex and my last period was the 5th of June but my periods are irregular so I don't know if this is just a period. I have had slight cramping and some mild back pain and pain in the tops of my legs and have been feeling tired but that's it. I have taken pregnancy tests a few days ago which were negative. I'm so worried can someone help.