Can Missing A Birth Control Pill Cause Spotting?

I m currently on birth control (Microgestin 1/20). Last week I missed a pill but took it the next day around the time I m suppose to take it. Ever since then I ve been having spotting. At some points the spotting goes from light brown to red like blood then brown and keeps doing this. I did not have sex the day or a few days after I missed my pill so I don t think I m preganant. I just want to know if this is normal.