If it's brown it's old blood. And having sex the 2nd would put you pretty close to Ovulation so I would just hold on and test again in a few days. But also stress and other live choices can affect your cycle I wouldn't worry to much but if you don't have your menstral by next week I'd call your Dr to do a blood preg test. But I wouldn't worry
Oh and i do have some pregnancy symptoms : very tender breast, gassy ( more than usual), and light cramping/ pressure in abdomen