It is called Excited Delirium. (not dementia) Not uncommon with cocaine use and now we are finding when on Fentanyl & speed as well. Typically the user will go from the happy go lucky to violent panic in a snap. Just like at Wendys.
Also there is Wooden Chest Syndrome that is an identified side effect of Fentanyl even in clinical use. WCS paralyzes the diaphragm making it difficult to breath while you are still conscious. Therefore one might say “I can’t breath”.
This happened to a neighbor of mine. According to witnesses, the first thing the paramedics did was sit on him to try and hold him still. The rest of his treatment was administered in the morgue.
That would explain why the medical team that arrived on site were Sheriff Deputies and not the regular EMTs