Unfortunately I found out the hard way unless you are unable to care for yourself at home, even if you suspect als is the cause, the ER can only do so much. Even if they run tests they usually cannot diagnose you with als. I’ve read some case studies of diagnosis at ICU but only after respiratory failure and done by a neurologist that they called in to diagnose. Maybe your ER will be more extensive but I wouldn’t be surprised if they discharge you with muscle relaxers/opiates/Benzos for any pain/anxiety.
Best not to be hooked on addictive medicine but if you have too much anxiety until your neurology visit then don’t feel bad taking anti-anxiety medicine in the interim. Keep us updated, hoping for the best.