Suggest The Dosage Of Tylenol To Be Given For 12 Year Old

I have a 12yr old daughter. 5 ft tall. 125 lbs. born w/myelomeningocele. she has had 13 surgeries to correct her health problem. she had the opening in her back repaired, VP shunt, bilat. ankle tendon release, tendons behind her knees released, chiari decompression, spinal cord untethering, VP shunt revision, VEPTR w/revisions every 4-6 months and January '10 had a total spinal fusion. my question: she is having some "normal" pain. she was previously prescribed Tylenol w/codeine after 1 of her many surgeries. i currently have tyelnol #3 but she has grown alot and I am not sure what her dosaage would now be. hope you can help