kellymom is a great resource for all things breastfeeding. Here is their list of AAP approved meds and the safety during breastfeeding.
Breastfeeding or not, I personally try to avoid too many meds for a simple cold. You can take ibuprofen or tylenol for the headache (I'd take ibuprofen, I find it's more effective). As for the congestion, I'd keep using cough drops and use saline in the nose (I actually make a saltwater mixture and just snort it up one nostril at a time. Works like a charm). You can also buy little bottles of it in the stores or use a neti pot. Use a humidifier or get a pot of steaming water and put your head over it with a towel "tent" over your head. I also drink a lot of hot heat when sick, and it's very soothing.