Glad the gp gave you some scripts to help, hopefully they kick in soon. I suffer from terrible hay fever and have constant sinus infections whilst pregnant, they're incredibly painful so I feel your pain. I definitely find resting helps, thogh i know much easier said than done when looking after young children. I'm sure you do anyway but I also avoid reading or screen based activities (TV, computer etc) as I find the strain causes pressure, and a good old fashioned eucalyptus steam (head over bowl with a tiny dash of eucalyptus oil in boiling hot water) helps too.

I hope your scan is helpful, I'm curious to see what course of action they recommend afterwards!