birth control pill problems?

I recently started on birth control for the first time, I'm 19 years old so I've never been on any other pills before. They said I could have some bad symptoms and I could change pills if it becomes a problem but in not sure if this is caused by my pills or not. for the past 2 and a half weeks I've had the worst symptoms I've ever had, headaches, nausea, non stop cramps, mood swings, hot flashes and lots of fatigue. I was also supposed to start my period 4 days ago but it never came and instead I'm having about 2 table spoons a day of this sometimes brown but mosty black gooey stuff coming out of me. That's been happening for a bout 5 days now, I thought I was just spotting a weird color for my period but I don't think it would have taken this long for it to come and I'm not sure if it's like dry blood or something. I'm waiting to hear back from planned parenthood about my problem but I'd still like to now if this has happened to anyone else before and why. I tried to find something like it online but came up empty