An assessment for an underlying cause of behavior is needed before prescribing antipsychotic medication for symptoms of dementia .  Antipsychotics in old age dementia showed a modest benefit compared to placebo in managing aggression or psychosis, but this is combined with a fairly large increase in serious adverse events. Thus, antipsychotics should not be used routinely to treat dementia with aggression or psychosis, but may be an option in a few cases where there is severe distress or risk of physical harm to others.  Psychosocial interventions may reduce the need for antipsychotics. 
That is a horrible experience and I know it all too well. Mine may have been less severe than yours, but it was probably the most painful thing I have EVER experienced. Last October, I was in the hospital & I was kinda freaking out a little, so they involuntarily gave me Haldol to relieve some of my anxiety. Mind you, I was 5 months pregnant at this time. I’ve taken it b4 & had issues, but never this severe. If I take benadryl or cogentin w/it, I’m usually fine. It all started w/ a stiff neck & then back. Then my face began to tighten & i had involuntary spasms of the face. My neck was so tight that I experienced the same thing as you… my neck was turned completely sideways & trying to go toward the back of my shoulder as well. They did not want to give me either cogentin or benadryl b/c of the pregnancy. It progreased very quickly & I was crying in agony. They thought I was faking it up until they finally gave me some cogentin thru my IV & I had complete relief in less than 5-10 minutes. However, my muscles in my neck & back were very fatigued after that. I never want to go thru that EVER again & I now list haldol as an allergy on all my medical records.