Ugh sickness - gross, sorry.

I'm 27 weeks and I have pretty bad allergies (to trees, etc). Lately I've been waking up in the middle of the night coughing. I start to cough up phlegm, which then triggers my super-sensitive gag reflex and leads to puking several times. Once I am vomiting, the phlegm (clear and stringy) all starts draining out through my mouth and nose. It's crazy. Has anyone else experienced this?