Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
Seek emergency care for severe trouble breathing, chest pain, fainting, severe confusion, inability to pass urine, or rapidly worsening weakness.
A suspected pain-medicine overdose also requires immediate help.
In the United States, Poison Control can be reached at 1-800-222-1222; call emergency services if the person is unconscious, having a seizure, or having difficulty breathing.
Contact a healthcare professional promptly for visible blood in the urine, new flank pain, fever with urinary symptoms, repeated vomiting or diarrhea, worsening swelling, or a noticeable decrease in urine output.
These problems may need same-day assessment.
Routine follow-up depends on the degree of kidney damage and whether kidney function is stable.
It may include blood pressure checks, creatinine and eGFR testing, urine albumin measurement, and periodic review of every medicine and supplement being used.
The article also says
Keep an updated medicine list and bring it to appointments.
Include nonprescription pain relievers, cold remedies, sleep products, vitamins, and supplements.
Ask before restarting a medicine that was stopped because of possible kidney injury.
Every sign above is quoted from the sofidex article on Analgesic nephropathy. If you are not sure, err upward — it is always reasonable to be checked.