Not due for 17 days

Ok so I have always been irregular and I have another app on my phone saying I'm due in 17 days. Well last night went potty and had light brown discharge when I wiped. Then took my dogs out to go potty and experianced bad cramping...... Went away after few mins then was fine rest of tonight into the morning.... Well I got to work and had to go around 9 when I went was blood on my undies!! Should I call dr obgyn or wait it out??