Hello & welcome, I am Dr. B, a licensed veterinarian and I would like to help you with today. I do apologize that your question was not answered before. Different experts come online at various times; I just came online, read about your wee one’s situation, and wanted to help.
Is the whole neck swollen or just under the jaw?
Are his gums pink or pale/white?
Is this compromising his breathing?
Does it feel firm, fluidy, warm or sore to the touch?
Any chance of an injury or insect bite? Any drooling?
Can you take a photo of this to let me see what you are seeing? To post a photo, you can use the paper clip on the tool bar. Or if you cannot see that on your phone/computer, then you can post them on any site (ie Flickr, Photobucket, Imgr etc) and paste the web address here for me to have a peek.