What Could Cause Severe Swallowing In Throat After Taking Antihistamine Medication For Runny Nose And Sneezing?

Last Thursday and Friday I was suffering from what I thought was a head cold. Runny nose, lots of sneezing. I used antihistamine medication (OTC) and seemed to have all cleared up. This morning, at breakfast, I felt a small pain in the lower right side of my throat, at the top. Now, 10 hours later, my left gland is swollen almost to the size of a golf ball. It's becoming hard to swallow without discomfort. What should I do? Is this serious and should I seek immediate medical attention via emergency room? Larry Tyma