Pregnancy Symptom?

Okay ...

So I've heard having cold like symptoms can be related to pregnancy. Is that true? How soon after the egg is fertilized can this symptom occur? AF decided to leave for days ago. We have been TTC but I honestly do not think I am. I receive a BFN on my last two test. Which were the day of AF (cause I was spotting) and after AF left. I've also have had some abdominal and back pain this morning. I've also been experiencing terrible indigestion, constipation, and horrific gas. I really would love to be pregnant. But I am feeling a little pessimistic. Has anyone else experienced anything like this?