H.F.
It could just be the return of your period along with the stress you are experiencing. However, I wouldn't discount pregnancy yet.
But here is my big advice. Call your doctor and let them know what is going on. It may be nothing to worry about but if they continue for a set period of time they may want you to come in and have some tests run. They may also want to run another pregnancy test.
Anyhow, I wish you the best of luck with this and hope you are feeling better soon.