RE: treating DD's first cold
For the nasal congestion, we've had good luck with squirting breastmilk up DS's nose (a few drops) prior to using the nasal syringe (loosens things up considerably). If you aren't BFing, you can use saline drops I believe to do the same thing. It really helped get the gunk out when it wasn't coming out on its own.
THe PP's link to Dr. Sears site is great. The "call your doc" thing is just cover your butt from the manufacturer...you should be fine following Dr. Sears' recommendation on dosing for her weight (especially at 8 months of age).
Hope your little sweetie is feeling better soon.
Mama to DS-2004
and a new addition-ds born march 2010