help I need questions

I just found out I'm pregnant yesterday and I have been having some bleeding it goes from light pink to kind red than it has little blood clots the size of a marker tip. But the doctor said it's just implantation bleeding . Has anyone had this problem before and if so give me details . The doctor has not checked me yet she just hgave me a pregnancy test until I go back than they will check me . I get cramps also here and there.