AF or Implantation

Im 3 weeks post HSG. Last week I was full sure I was PG (sore breasts, slight nausea, tiredness) then AF arrived 3 days early. weird things is it only lasted like 3 days (normally 4-5), medium flow (normally heavy the first couple of days). im at about 4 days after it finished and I'm not even joking guys I'm so dizzy I can barely stand and I'm so tired, breasts still pretty tender and I'm bloated 😖. slight cravings for lots of sweet treats too. Was I having AF or Implantation bleeding. would love your advice ❤️