I used nasal spray with all three pregnancies. I had a really bad case of rhinitis and used Vicks or Otrivine drops, with my doctors blessing. The only thing to watch for is that if you use too much it can actually make the problem worse. Obviously you need to check with your doctor first. If he thinks you really need it, he'll advise what you can take.
There are some tablets available, but again, you have to consult your doctor and use in moderation.
You could also try a saline nasal spray, although I never found them much use.
Hope you feel better soon.