difficulty is a noun, difficulties is a plural word of it
Dyspnea is a symptom of pneumonia and tuberculosis
there are not enough resources to do a job effectivly e.g not enough doctors to run a department effectively and efficiantly. There isn`t enough information on seizures to tell them apart. there...
'any difficulties' is plural, 'any difficulty' is not. e.g. 'difficulties' represents more than one problem, 'difficulty' represents one