What Causes Swelling Of Breast,cramps And Irregular Periods After Taking Plan B?

Hi. I'm 18 years old and I have one partner that I'm sexually active with. One time I had unprotected sex and I took the plan b pill. Since then, I have had swollen breast, cramps and my period three times in one month! I feel like this is a lot of blood and I don't know what to do, I went into a walk in clinic and the Doctor assured me it was normal. Is this normal? Should I go to a Hospital?