from my own experience...when my crohn's is flaring...all of my lymph nodes swell and are tender to touch.
Has he been checked for mono? Usually lymph nodes swell in a localized area..With crohn's unless he has problems in his throat from it, I wouldn't think it very likely. I know this because my doctor told me that my digestive problems probably aren't related to my own swollen, neck lymph nodes that I have had for over 6 months. Lymph nodes would swell closer to the inflamed area, which would be in the abdomen usually. Some times lymph nodes swell for no apparent reason..But usually when they swell in the neck its an indication of something viral, like strep throat or mono. Or it could be something bacterial that will require anti-biotics. The fact that there painful and tender is because lymphnodes can swell up very fast but will take a couple weeks to a month to go down. This is good that there tender and not hard. Hard lymphnodes i've heard can indicate a tumor somewhere close by. Bottom line though, it's probably nothing too serious. When I came down with strep throat I really didn't feel sick, I just felt a little more tired than usual. So he could have something like that and not really notice symptoms. Just take a trip to the family doctor and talk to them. Best of luck to ya'll!