Spotting..Lower Back Pain

[punkrockmomma]

I'm about 6 1/2 weeks pregnant. My boyfriend and I had intercourse last night and when I woke up this morning around 8 I noticed I had white mucus that was colored light pink and noticed a few light pink spots. I called a nurse and she said this was common in an early pregnancy especially after intercourse. I went on the rest of today with lower back pain and no more bleeding until about an hour ago when I went to the bathroom again, I noticed dark red spotting and a small pea sized mucus type of blood clot. I've had a few drops of blood here and there since. Is this type of bleeding accompanied by back pain normal, or should I prepare myself for a miscarriage? I don't know what to think and this is my first pregnancy.