what helps me with my sinus issues on a daily, preventative basis (sounds like you're in more of an acute situation) - just in case any of this will help, i'll list it (some of it comes from consultation with a naturopath, others are things i've read about and tried over years of sinus issues):
cod liver oil, the equivalent of a teaspoon daily. i was taking nordic naturals capsules, but someone gave me a bottle of prenatal stuff recently and it works just as well. for me this helps keep most of my respitory/nasal inflamatory reactions from even starting, which is great, but if i'm already clogged up i need additional help.
honey - also a teaspoon daily (in tea, on toast, plain if you like) - as local as you can get it. this is also more for soothing and minimizing inflamation/allergic responses to allergens.
saline nasal spray
applying pressure to sinus pressure points in my armpits. make a fist and fit it into the opposing armpit. hold your elbow and push into the pit as hard as is comfortable. after a couple of minutes your opposing nostril will clear. this is temporary relief that i extend at nighttime by lying on my side with my arm extended stretching upwards underneath my body. pressure is applied from the weight of my body and i can breathe while i sleep. over time this has not been great for my back, but breathing is pretty important!
i do eat dairy and wheat, but when i'm having an acute flair up that is making me miserable i cut dairy out entirely and minimize the wheat, maybe only at breakfast giving my body a lot of time to process it. other times i'm okay if i just keep my intake of those things (and sugar) at a minimum. i love both dairy and wheat and can slip into consuming them very frequently. then i have a bad sinus issue, cut them out, miss them terribly, but end up feeling amazing and SO clear. there is a huge difference.
also, when not pregnant, i've used sudafed. i've read you can use it when pregnant, but i wouldn't personally. my last tough episode was a month and a half ago and every sinus cavity in my face was clogged or inflamed (jaw, teeth, all through my cheeks, nose and brow...) and i read an online article about tapping and rubbing in a specific pattern twice a day. it really did seem to help with the draining. if i can find it again i'll post it.
here it is:http://www.distanthealer.co.uk/sinus_sinusitis.htm
the method is described on that page and there is a link to a face chart to illustrate the method. there is some option to purchase something on that page... i never really even read into that area, the tapping/rubbing was enough. it wasn't some immediate a-ha, but helped over a few days.
good luck and i hope you find some relief! i know how painful and frustrating it can be!