Extreme congestion leading to nausea

Emily
Hi ladies!
I've had some really horrible allergies and sinus issues this year so far, starting about 3 or 4 weeks ago. I was almost nausea/vomiting free after a summer of hypermesis, but now I'm starting to get nauseated, gag, and occasionally throw up from so much post-nasal drip (sorry!). The pain in my head is definitely sinus pressure but I don't think it's a full blown sinus infection. 
I had my first nosebleed in my life last week and overall my whole head is totally congested despite steamy showers, a humidifier, changing positions during sleep, and gargling saltwater to soothe my throat. 
Does anyone have any pregnancy-safe suggestions? I'll be 18 weeks Friday.