I Have Very Serious Sinuses. Lately, I Feel Like I

I have very serious sinuses. Lately, I feel like I have to keep swallowing.. After a bit, I feel I have to spit up or vomit and all that comes out is nasty whit foam. It happens throughout the day any time of the day. Not because I've eaten or drank water. It just occurs out of nowhere and always just white foam. Never happened to me before. Nothing to do with occasional sinusitis. What's happening to me?