Bleeding in between periods

So I just had my period ended about 8 days ago. I recently went off birth control because we weren’t going to prevent having another baby. Today I noticed I had some brownish discharge (which sometimes I get after sex, which happen last night) so didn’t think much of it. Well later in the day when I went to the bathroom I noticed it had turned into a bright red blood like I get during my period. I wouldn’t consider it spotting because usually when I spot it’s much much lighter (like a light pink) but this was bright red like my period usually is. I was a little cranky feeling for like 10-20 minutes but then it went away. It just feels like I’m going to have my period. I’m a little concerned because I have never bleed in between periods like this. Idk if it has something to do with going off birth control, the sex, both or what but I’m a little concerned. Has this happened to anyone else? I will be contacting the doc tomorrow.