I have the same problem and I'm fine. It might be hormones or prenatal vitamins.
When i was 3-5 weeks pregnant that happend to me too but my doctor told me not to worry, But you should check with your doctor to be sure :)
Sounds like a UTI , talk tovyou doctor about it , i had the same problem and my doctor prescribed me medicine and it went away haven't had one since , i had it around 10weeks im 37.5 weeks now.