I had a cystoscopy and everything was fine, but three months later, I had blood in my urine again.

Doing cystoscopy is fine after three months and then blood in the urine, may be acute injury, urinary tract infection, urinary stones, urinary tract tumors and other factors.
1. Acute injury: some strenuous exercise, or the lower body suffered serious trauma, resulting in localized damage to the urinary tract system, there will be hematuria, may also be accompanied by swelling, pain and other symptoms.
2. Urinary system infection: due to the existence of infection in the urinary system, the infection is more serious, causing damage to the urinary tract tissues, can cause blood in the urine, such as acute pyelonephritis, acute cystitis, etc., which may also be accompanied by fatigue, fever, pain in urination, urinary frequency and other symptoms.
3. Urinary stones: when there are stones in the urinary system, in the process of position change or urination, the stones move and damage the urinary tract tissues, which can cause blood in urine, common diseases are bladder stones, ureteral stones, etc., which may be accompanied by pain in the lower back and abdomen, difficulty in urination, urinary frequency and other symptoms.
4. Urological tumor: such as bladder tumor, often manifested as painless hematuria.
When the symptom of blood in urine occurs, we should pay attention to it and consult doctor for examination and treatment as soon as possible to avoid delaying the condition.