Never ending congestion

My son has had a cold for about 3 1/2 weeks now and I took him to the doctor about it last Monday and my pediatrician told me it was completely normal and would go away. Now it’s a week later and he still is so congested and has developed a cough. I do saline spray with the nose frida every time I hear the congestion. I put on a humidifier at night right by his bassinet and nothing is working. Do I take him back or just let him get over it himself? I’m a ftm and just want my little man to feel better 😰