Lots of different things that could be causing these symptoms. They could be related to the new medication that you took right before the symptoms started. Some sort of changes with hormonal medications such as that are to be expected, and you could discuss that with your doctor
or pharmacist. Heavy exercise can also cause some changes, as that will lead to hormone shifts as well. There are other things such as fibroids and many other conditions that are quite varied and need more information before they could be suggested. Your doctor will be able to give you the most specific information by asking you the appropriate questions and perhaps completing a physical exam. Bleeding
and spotting outside of your normal cycle is not something that should be ignored, so please speak with your doctor about this question.