hi

i am 23 yrs old and have a white smelly discharge coming from my vagina for almost a week and now i have been experincing severe burning sensation while passing urine for the past three days.i assumed it is an uti so i had lots of water and had noritel. today i visited a doc she gave me medicine o2 and pan for five days. also i have been given cansoft to insert. firstly i want to know how to insert cansoft and if it will hurt ? i am sexually active and i wish to know if this is an std? though we always usas been protection there have been a few instances when we havent but my partner did not come in me. i checked using a home pregnancy test the next few days and it was negative. my second question is how reliable is the home pregnancy test. thirdly my periods are not with regular with large gaps from 2 to 6 months . i want to know if this medication will help none the less? and also how do i keep a check of my pregnancy from time to time without having a regular menstrual cycle ?