It sounds like you are probably dealing with a case of nasal allergies or sinus congestion, both of which can lead to this persistent stuffy nose.
A humidifier can help in some cases of nasal congestion. They do this by preventing drying out of the nasal passages at night while you sleep, which can lead to a reactive 'rebound' congestion in the morning.
However, I think you probably need to consider more definitive treatment of your nasal congestion as well. In particular, if there is a component of allergies or sinus involvement here, then you really need to target those causes if you want to see your symptoms improve. For example, both sinus and nasal allergy problems are best treated with a combination of anti histamine medications and nasal steroid sprays. These are medications that your primary care doctor
can prescribe for you, if they agree that this is a useful line of treatment to pursue.
In general, I would avoid over the counter nasal decongestants, as these only work for a short period of time and, if used chronically, may actually lead to worsening of symptoms.
I suggest that you go see your primary care doctor about this issue again for additional help along the lines I mention above.