High APTT! rest other values are normal.

Hi! I am 34yrs old male. I have slight nose bleed episodes from last 9months. Around 2 to 3 times in a month i see 5-6 drops of blood each time from my nose. I have done my CT. It came out to be normal. Then ENT doctor suggested for aptt test it came as 49.5. Then Doctor gave 3 Vitamin K injections for three days. Then aptt came normal. After 1mnth same thing continued. I again went for test. Now my aptt came as 39.1 which is slight above normal range. My Aptt is increasing on its own. I have consulted haematologist as well. She asked me to do Aptt mixing studies test which I did in which all parameters came normal except Aptt value. What to do now? What can be the reason of increasing Aptt? Which doc should i consult now to stop bleeding and makin aptt come in normal range?