Sad and frustrated

I’m pretty sure I am having a miscarriage. I tested positive on Monday and then today had about 30 minutes of bright red bleeding. Now I just have a light brown discharge. Doc said to go to OB ED to get checked out. The pregnancy test there was negative so they basically did nothing and told me I was probably never pregnant. Well I just got home and tested again and it was still positive. I’m pretty sure I’m still losing the pregnancy but I don’t know what to do. Why do people treat this like it’s nothing? I feel like I can’t breathe.