Hello Thanks for query . Burning urination and slight blood in urine could be mostly due to UTI and side effect of Aspirin that he is taking . There is no urgency to meet urologist . Get his urine routine and urine culture done and take appropriate antibiotic as per culture report . With held Aspirin for couple of days . Ensure he drinks more water to keep his urine dilute . If problem persists consult your Urologist . Dr.Patil.