How To Clear Blockage In One Nostril In Asthmatic Child?

Hi. My 12-year old daughter has asthma & a number of known allergies (cats, certain grasses, house dust mites etc). Over the last 8 years she has had a number of different meds to manage all this (some successfully, for a while and others not). She seems to be outgrowing it (we re down to 1 or 2 doctor visits a year, with occasional use of duolin in a nebuliser). She s now sneezing a bit but is complaining about the left nostril being completely blocked. She rinses regularly with saline but apparently it s now blocked to the extent where the water doesn t go properly through from the right and out of the left side. I m also concerned that she doesn t seem to be able to smell well. What else can we do please?