Opisthotonos due to tetanus or meningitis... or possibly a special case of cervical dystonia or cerebral palsy (PS: there's something that looks like vomit on the bedsheets, so it can be a case of poisoning - metals or some drug, for example)
Correct answer: Indeed, arching of the body and neck hyperextension is called opisthotonus, which is characteristic for a severe tetanus infection. It’s also true that meningitis or strychnine poisoning can cause this, but in these cases opisthotonus is less likely to occur.