K.
First, I would definitely call the doctor. My sister had some bleeding and did end up having a miscarriage. It's always better to play it safe.
As far as quitting your job, I believe you need to do what you feel is the best for your family. If you do go back to work you need to also factor in the expense of daycare of babysitting. Most nannies I know of make a minimum of $10.00 per hour. I am not sure about benefits. Hope that helps!