Type O+ here as well. I spent years feeding an ear, nose and throat doctor to deal with sinus problems. After reading Eat Right for Your Type, I started eliminating stuff on the "bad list". It turned out that wheat was the primary source of the post nasal drip. A wheat free diet leaves my sinuses clear all the time...except when I catch a legitimate cold. Fresh milk was another item eliminated. The gasto-intestinal distress that was almost constant went away with elimination of fresh milk. Total elimination of dairy also fixes the swelling in my throat. It makes life challenging to keep all the bad stuff away.
When I eliminate the bad stuff from ER4YT and follow an Atkins low carb diet, I can lose weight and stay exceptionally healthy. A little regular exercise helps a bunch. Russian kettlebells are my exercise of choice.