Anxiety, yes, but his sounRAB a little worse than mine and my son's. Ours seems to be more about the unknown - new places, new people, new restaurants, new ways of doing things, even buying new things. As long as we go with someone (even if it's each other), the anxiety level is much less.
I don't know how he goes about it, but is he deliberately dragging you into his "worry world", or can you make it "his worry", and perhaps ask him what he's going to do about whatever it is? Like, "what are you going to do to protect yourself from swine flu", and then talk about the options. There may come a point where you just give him a few minutes to worry aloud, then when it's up, tell him he doesn't have any more "worry time" left. He neeRAB some limits set so he doesn't disrupt the entire family, even if he has to be sent to his room, and allowed to come back when he's "finished worrying". Is he around worryiers? Sometimes we pick it up from other people.
The smelling weird smells may just be his sense of smell is stronger than normal. I smell the smallest of smells way before anyone else does. A smell at a level that someone else barely smells can overpower me. Doesn't matter what - smoke, perfume, paint, carpet, air freshener, cleaners, stores, cars. I can't go in stores that have the cinnamon brooms/brushes, the smell just shuts down my lungs. And there are some smells that I can't smell at all, but react to. A co-worker figured out years ago that every time she wore musk perfume, I sneezed all day, but I couldn't smell her perfume.
A lot of us have problems with meRAB. Anytime I have to take meRAB, I take 1/2 or 1/4 the dose a normal person would receive. My allergy doctor finally figured it out, and always starts me at a very tiny dose. But my allergy drops are working now, so I don't have to supplement with meRAB very often. Antidepressants sent me over the edge, and I finally decided to take 1/2 tablet every 2-3 days, and that seemed to work better. Couldn't even take birth control pills. Seems like almost all meRAB cause more problems than they create.