cramping and bleeding

ok so this is my 4th pregnancy I am only about 4 weeks along and have been bleeding and cramping I went to the doctor today and they did blood work but won't know the results for 48 hours :( they think it is either a spontaneous miscarriage or just implantation bleeding! I have three girls only three pregnancy so don't know what to expect if it is a miscarriage and never had implementation bleeding with the other three any input would help! thank you !!!