Worsening symptoms, when to consider ER? Feeling very scared right now

Last two nights have a symptom that I feel may be an emergency? I'm trying to sleep completely vertical I slowly feel what I can describe as a 'mush' slowly creep up my esophaguses. It happened last night, and now it's happening again. To give a better picture: I lay down on my wedge and use two other pillows to further elevate myself My GI appointment isn't for another month. I'm starting to become very worried. Nothing about this feels right and I wonder how much damage I'm doing to my esophagus by prolonging it. I don't know if this is how normal heart burn feels like, but the fact that I need to be completely vertical to sleep is a worrying sign to me. The last time I ate was 6:30 PM and it is now 12:42 AM I have some Gaviscon Advance on the way but god I feel like hell. I don't understand how I have developed such a steady stream of worsening symptoms in two months. I'm very sorry for making so many topics but this is the only place I have an outlet for this.

Edit/update: So I ended up going to the ER yesterday because the mush sensation was persisting even when I was 90 degrees. Lower ribcage pain was also more present. They took my blood in like five different vials and the doctor ordered chest x-rays. After relaying my symptoms to the doctor and the nurses, after awhile the doctor came back and said everything looked good. The doctor ordered me a "GI cocktail" which tasted awful but did wonders for my throat and the pain in my lower ribcage. In the end I was diagnosed with Gastritis. The doctor told me they would be sending a prescription in for the same type of cocktail and to get back on the PPI I was initially prescribed. I'll still try to get on the GI waiting list next week.