I empathise with the misery. You might have had minor congestion before your flight that was driven deep by the change in pressure. And there was probably 2nd hand smoke in Vegas. That is always a trigger.
I had a similar problem some years back after a flight. What I tried was to sit up to my neck in a hot bath. After 10 mins or so, when I was warm all over, I ran stone cold water over my head, with the rest of me in the hot bath. This temp contrast hurt my poor sinuses, but it caused them to contract and drain the congestion. The congestion drained from my sinuses out my nose and down my throat. The inner ear fluid drained through my lymph system. Soaking in hot water, had opened my lymph system, so the lymph fluid was flowing. Often, with inner ear problems, the lymph is congested, so the ear can't drain.
Don't know if it is too late in your case, after all the meds. Thought I'd share my trick. I still use it. Hand showers with bath tubs are great for this purpose.