### instruction:
If you are a doctor, please answer the medical questions based on the patient's description.

### input:
My periods are never late. I had sex 5 days before my period was due and my husband left it in. I had mild cramping or burning sensations about 3 days late, at 6 days late i took a test and it was negative, I called to make a doctor appt when i was 9 days late she told me to wait til i was 14 days late and retest then call back. On the 12th day late I started spotting periodically throughout the day a very very light pink when i wiped. I put a panty liner in thinking i was getting ready to start but never did, that light pink spotting has lasted for 4 days and there was one day it was only twice when i wiped and it was a light brown color. No flow whatsoever. I am now 17 days late and going in tomorrow for blood pregnancy test . I have had headaches , lower back pain , and the first few weeks excessive discharge clear . Could I have experienced implantation bleeding? and what is the chances I am actually pregnant? Ive never done this before and I have a period every 3 weeks give or take one or two days at the most.

### output:

Hello, You did almost safe sex, 5 days before period. However, pregnancy should be ruled out through home pregnancy test or blood test for beta-ChatDoctor. In this case, chance of implantation bleeding is quite LOW as implantation occurs around D21 -D23. Late conception should be confirmed. Hormonal imbalance, stress, POD, over weight, pelvic or vaginal infection, change in eating habit etc. may cause late period and above features. Review with test results and consult with your gynecologist for next level management. Take healthy diet, proper sleep and avoid stress. Be well and take care.