Sertraline experience

Hi there i take Sertraline 100 mg since 8 months in July i did a huge mistake , i did not have enough medics so i took 50mg for 3 days Till i get New package and then again to my normal dosis 100mg..it was hard as if i start from 0 then stabilized some days with bad days now iam in my 6 /7 week and i feel hell after i had very good weeks is this normal??anyone experienced this??pl answer me.