very early miscarriage

Need some opinions. So my other half and i baby danced at ovulation. i was 10dpo on Saturday and had what im sure was implantation bleeding. the bleeding ended the same day. i woke up Sunday morning with tonsillitis ans got perscribe antibiotics but may the doctor aware we were trying for a baby. on my second dose i started back ache and cramps and then started heavy bleeding. my period isnt due till wednesay. is this likely to be a miscarriage? iv read antibiotics should be ok but iv been running a fever also. Thank you