Could Heavy Vaginal Bleeding Along With Blood Clots Be Due To Miscarriage?

I had unprotected sex in November had regular period then had sex after had all the signs and symptoms of pregnancy but went away took pregnancy test neg period came on but was irregular bleed heavy first day pass small blood clot then bleed light only stayed on for 4days normal 5days heavy to preg test neg is possible i miss carry but now feeling alot of fluttering