Is it possible to get a false positive?

Brit
Okay my period was due on the 24th I took a test and it was negative It's now the 28th and no AF my boobs are so sore I can't stand touching them I've been crampy too I took a test this am and it looked negative but when I looked to it again after I woke from my nap it had a faint line on the positive part Is it positive to get a fake positive? And does anyone else see the lines?