Hello and hope you are doing well.
You need to go to the hospital for a proper urine analysis and therapy. Kidney function tests will further help in assessment. It needs to be seen what the tissue is and therapy will be decided after proper assessment. So, please consult your doctor regarding this or go to the ER.
Hope this helped and do keep us posted.
It's only considered pre-existing if you have been treated for an ongoing problem with your kidney. Individual kidney stones cannot be considered pre-existing. Get a ct scan from a doctor then talk to a urologist if it is a kidney stone. I was born with a condition that causes my body to create kidney stones. I have been to the emergency room 4 or 5 times in the past 18 years for the large stones, small ones pass ok. My first stone caused bleeding and severe back pain also with pain in the lower abdomen area along with hot/cold flashes and vomiting. It may feel like someone is squeezing your kidney while at the same time stabbing it with an ice pick. I first though it was my appendix. I was wrong.
Water, water, water. I have to drink plenty of water every day. This helps to flush it out and to keep the kidney tissue from squeezing the stone. Drink enough water to make the urine light yellow to almost clear. Stay away from soft drinks if you can help it and processed foods high in sodium.
I currently have a large one in each kidney right now around 7mm-8mm in size which may require the doctor to blast with ultrasound.
I have passed at least a dozen small stones over the years. Products with citric acid, mainly lemons will help prevent new one from forming although it will not help any current ones.Good luck.