My sis unfortunately gets kidney infections all the time. They're relatively serious so get it checked by a doctor. Not this one...
Seriously, symptoms are:
Pain lower abdomen (she says it's like period pain, not like I'd know)
Temperature
Raging thirst
Possible pains in sides
Urine heavy or cloudy
Hard to pass urine
You need an antibiotic so don't try self-medicating. You should probably also give a urine sample.