Ok so at the beginning of this month l was worried l could get pregnant so l took the plan b. Now l usually get my period every Sunday morning so when it did not come l was worried and today l got a pregnancy test done. The test came out negative and a couple hours later l got my period but its a black color. Could this have to do with the possibility l was pregnant?

Yes, it is possible that this could have been related to pregnancy. Because you took the Plan B it is also possible that it could be a side effect from the Plan B (an example only).

l would recommend seeing your doctor for further evaluation of the situation to see what they say.