when is the bleeding going to stop!

Since I have gotten the depo shit on January 10, 2018 I have been spotting. these last two weeks the bleeding would stop for a while day and by the time night come dark blood will come out. some days I will go a whole 24 hours with out bleed but I wear a pad just in case, but the last two days the dark blood will continue all day. I don't know if I should see the doctor or is it normal for it to be like this.