These black specks can be due to insufficient water intake, urinary tract infection (UTI) or kidney or bladder stones. You need to get a urine examination and a ultrasound kidneys and bladder done to confirm the diagnosis.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.