implanon- bleeding, pains and vomitting

i am on implanon, i bleed one week n then the next week i have sharp sharp bad pains and my period come on again. I go see my doctor and she prescribed me Estradiol to stop the bleeding. Then an exact week later i bleed again and my back have pains and i vomit or sometime feel like i have to after everything i eat. what could this be??