Bleeding After Intercourse

I am 15 weeks pregnant and my husband and I had intercourse three days ago. When I went to the bathroom after, I noticed there was blood (light pink) in the toilet and on the toliet paper when I wiped.  I called my midwife and she said to keep an eye on it and as long as it wasn't bright red and a lot of it I should be fine. Well yesterday and today I am still spotting a dark brown color and I have called my midwife again today and she says that it's mostly old blood but I am on the verge of freaking out and going to the emergency room. Has this happened to anyone?