Thickened liquids and drinking through a straw as well as not tipping the head back helps prevent choking in my case. Temperature of the liquid or food seems to be a trigger. Anything near body temperature is toughest, so cool or warm/hot goes down best.
Waking up choking on your own saliva is something that you absolutely need to get checked out ASAP. Asperating fluids into the lungs to any degree, but especially to the degree and frequency that you describe is a huge concern.
Please get checked out, even if you have to go to the ER.
In my thoughts and prayers that an effective solution is found quickly.
With love, Erika