Hello! Welcome to HCM.
This must be worm infestation as you haven seen some movement in stools.
Many such patients come to my clinic, to whom I advise stool routine & CBC.
For you I would suggest stool for occult blood as you said its dark black in colour.
Anal itch may not be there necessarily in all worm infestations.
You haven't mentioned about fever
Consult your doctor for albendazole
treatment & further management according to the diagnosis.
Hope this helps.
Wish you healthy life.