What Causes Itchy Yellow Vaginal Discharge Post Pregnancy?

Dear doctor
I am 20years old female, 58kg and i had a baby girl 3months ago. I have been suffering from yellowish thick discharge, rush, itchness and pain when i pass urine since from when i was 5weeks, i had taken treatment(antibiotics) 8 times, but it keeps on coming back, and we have been using condom during the pregnancy, but we hav'nt been intimate since the baby was born because of this problem. Please doctor help