Bobert, if your sinuses are infected, you probably do need antibiotics - the doc is the one to judge.
When you've got them, you might try a couple of other things:

1) Neilmed make a squeezy plastic bottle that comes with ready mixed saline powder; you boil water, let it cool to tepid, fill the bottle to the fill-up line, add a sachet's-worth of saline powder, shake and then squirt it up your nose. A lot less unpleasant than the other various ways of doing this, and it gives wonderful relief by making the mucous membranes shrink back and clearing out infected gunge. If you suffer from blocked sinuses generally, it's good to use this every day.

2) The trusty hot lemon, honey and ginger (and whiskey if that's your inclination) will help you sweat it out if you take it before bed.

3) L-Lysine is fantastic for any viral infection - it's some class of a vitamin or amino acid or something; you get it in the health shop. Also works brilliantly if you have cold sores.

4) Kimchi, spicy if you can find it spicy, the Korean pickled cabbage is very good against colds. The Koreans also claim it cures Sars and bird flu...

5) Chicken soup is the traditional "Jewish penicillin" for colds; best is to take the bones of a roast chicken, add 3 big carrots, 2 onions, a quarter of a celery plant, chop the veggies roughly and add them in (no need to peel), put bones and veggies in a pot with lots of water and a bay leaf (and whatever other herbs you like), bring to the boil and simmer for a couple of hours. Leave the doors open so the vapour comes through; apparently the vapour of chicken stock has a great effect on the infected mucous membranes. Drain off the stock and make soup with it - if you're not feeling well enough to make your standard soup, just throw in a tin of kimchi into the soup and then gobble it up over a couple of days.

6) If you do get your energy back, make lentil soup with the chicken stock: peel and chop three carrots, garlic to taste, an onion and a bit of celery, and a couple of handfuls of lentils, and cook them in butter, turning to coat them. Add a bay leaf and pour on the stock, and I like to add one of those jelly type chicken stockpot thingies that Knorr have started making. Bring it to a simmer and keep it simmering until the carrots are almost soft; now add about half a cup of chopped parsley. You can whizz this up or leave the vegetables whole - nice either way. Also nice with a squeeze of lemon juice, and very, very nice served with cheesy wholewheat scones.

7) Get lots of rest, keep warm and snug, and get better soon.