Oxybutynin & 22 month old

My little one had hypospadius fistula repair. Anyway I requested something for his constant bladder spasms from the catheter and prescribed oxybutynin but I read that under 5 its not always recommended. Idk if should give it. He screams at night and thats because he's taking motrin and tylenol theres a 3 hr gap between each. Would you as a parent give it?