I'm terrified 20 weeks pregnant and spotting

So I started spotting last night it was a pinkish red I went immediately to the emergency room they literally didn't do anything they said it's normal that I'm OK the babies OK they wouldn't tell me the cause of the bleeding because it right now I was not buying it I told my husband I was going to go to my doctor in the morning so I called my OB the next morning. Which is today she told me to come in right away they did all sorts of test and ultrasound and everything looks perfectly fine with the baby and everything I just got my test results and I have a vaginal infection I asked my OB is that the reason why am bleeding she said she doesn't know she wants me to come back tomorrow I am worried sick I'm not getting any answers here they said it could be because of sex but I haven't had sex in a week she put me on bed rest until the bleeding stops has this happened to anybody and if so please share your experience with me i'm trying not to worry I was crying my eyes out last night when I saw that blood I don't want to get stressed out