Have kidney infection started feeling better but after doing errands yesterday i feel like i'm having a small relapse is this normal?

Not unusual : Whereas symptoms of simple, uncomplicated bladder infections usually resolve within 3-5 days of treatment, kidney infections more serious and often affect the entire body/system (fever/chills, nausea/appetite, fatigue/lack of energy, etc) and can take several (2-4) weeks before resolution. The other possibility is a true relapse of the infection and i would recommend a repeat u/a and urine culture.