My 4 week old baby is congested, coughing and sneezing, i have been using saline nose drops. she threw up mucus with her milk but she doesn't have a fever. can i use a nebulizer with saline water or only a humidifier?

Okay for saline: You can use a nebulizer with Saline Only - no medications at this age. Also use a bulb suction device to help clear secretions from her nose. When you are taking a shower, place her in her car seat and close bathroom door to give you both a nice sauna treatment as well. This first cold is always a tough one to get through - hang in there!