Appearance of positive line in pregnancy
test kit in absence of pregnancy can be seen in conditions like,
-errors of test application,
reading test afer suggested 3 to 5 minute window or reaction time,
kit with past expired date
-taking hcg injection
as part of infertility treatment
-in some diseases of liver, germ cell
tumors etc will produce elevated hcg leading to false positive test.
anyhow as you got periods it will possibly rule out the chances of pregnancy, so you better try in the next cycle.