What about a vaporiser?
I had the same thing in the 1st tri, and I knew that if it were safe to take a Demazin then I would've been sweet! But alas, it wasn't to be. It is very frustrating, hey.
Are you already having paracetamol? I did find it somewhat helpful in clearing my head a little. (Didn't do much for my nose, but helped me feel not quite as 'fuzzy' in the head.)
Hope you are better soon.