Can I Take UTI Medicines If I Am Pregnant?

Hi, I have just my UTI result earlier, just been from a Dr. now I just want to know; if its ok for me to take the medications, what if I am pregnant? But I do my pregnancy test at home that last week, the result is negative, but sometimes PT had wrong diagnosis, thats why want to know if I be going to take the medications b'cos had the pain in my lower abdomen, back in pelvic, and it bulging/lump a little in left side sometimes go right side lower abdomen..But I tell the Dr. that i'm negative for pregnancy test, thats why she gives me an order of medications, like clotrimoxazole..Pls. want to know, what i be going to do?