15 weeks

Hey I’m 15 weeks and 1 day I have been spotting its light pink but nothing heavy it does have a smelly odor to it this is my first time ever experiencing something like this this far in my pregnancy I have been pregnant twice before..I went to the ER yesterday and they said everything was fine the baby was moving and had a heartbeat but they diagnosed me with a threatened miscarriage and said that it doesn’t mean that I will have one but I’m not sure I’m scared because I have never went through anything like this so I don’t know what to look for or what to expect I haven’t been cramping but have had some back pain but I have had that since I found out I was pregnant, have anyone ever experienced this and should I be worried