I am a 23 year male. a brownish mucus like substance came out while i was urinating. i also noticed dark flakes settle onthe bottom of the toilet and other substance floated. i also felt a slight burn after i finished. what could it be?

Discharge: What you describe may be penile discharge. Especially if you had a sexual encounter recently with a new partner and it was unprotected, that would be especially suspicious. Another possibility is passing blood with your urine, but the description of such is not common in your case. One way or the other, get it checked out by a doc.

Urinary stones : You noticed brown mucus and sediment in your urine. You recently had kidney stone removal and stenting. You can expect sediment and blood tinged urine to resolve over time. Your doctor may have given you instructions on discharge paper of what to expect and when to call the office.

Burning pee: You must see a nephrologist as you must pee clear at all times. If sediment or painful urine is occurring your kidney is not functioning or you may have an infection that needs treatment.