I have had a cold for 3 days from 3 weeks. I've had terrible dry coughing, and I felt better before days. Its back but with phelgm, but weaker coughs.?

Try and see a doctor. If you can to determine if there is an infection in addition to the cough as you can take an antibiotic if an infection is present. Chicken soup and making sure your hydrated is a good idea as well. Some docs like cough medication, but i notice some don't so - that will be decided on by the doc if your an see one.