Thanks for the query.
and cold are common infections, they have to be carefully treated in pregnancy
as they can lead to complications like spotting as you are having.
Better to use house hold remedies to get relief.
For more details:http://srsree.blogspot.in/2012/05/cough-in-pregnancy.html
If the spotting persists better to use progesterone
supplementation, antibiotic course to prevent miscarriage