I live nearby and my family experiences similar cough/ congestions/ runny noses too. The problems generally start (for us) in late summer and go through fall. My daughter and I had good success with Nasonex (sp?) but there are dozens of different meds out there and you have to try several before you get the right one.
When we moved to this area from the Dublin, we began experiencing the problems. Never had them before. When I questioned my doctor, he said, "Welcome to Drip Valley". He said this area is known for allergy related problems.
A few things you might consider trying. First I would begin tracking the symptoms to see if they follow any pattern. Are they worse on days you spent playing outdoors? Did your symptoms get better while you were out of town for the weekend? There are websites that will tell you what is blooming in your particular area.
I would try a Nettie Pot. It rinses your sinuses and gets out the irritants. You can buy them at any pharmacy and once you're used to the sensation, it helps a lot. Our Dr also recommended showering before bedtime. It gets any allergens off your body so you sleep better. Also the steam helps loosen up the gunk in your sinuses.
I would also go back to the Dr. They have ways of telling if its due to a cold or allergies. Something about the color of the tissue inside the nose and around the eyes.
Good luck to you and your family.