I've Been Coughing Since September. Clear Mucus From Nose,month Running

I've been coughing since September. Clear mucus from nose,month running eyes. Also have tiny red bumps on legs with rash on arm. ENT stated reflux, next visited GI and stated coughing is not due to reflux and chest X-ray good. Stated I had mild gastritis. Changed plod pressure med and still coughing. Saw an allegist and skin test, environmental test, food allergy, inflammation, immune and red and white cells all good. Bacteria nose test with Ent negative. What is this?