So I was suppose to start my period but instead I am having brown discharge and slight spotting. Could this be a sign of pregnancy

There are no clear early signs of pregnancy (other than the intense pain of ectopic).
You might be, you might not. Just keep testing.

The spotting might be an early sign of your period about to start, which happens for some women. Give it a bit more time and see if you have an actual period or not. Test accordingly.

Could be a sign of a std just go get tested