It won't stay in your system long, that is why when used to treat an infection, in your case UTI, it needs to be taken every day to keep the levels up or it will not work. If there were an adverse reaction as well to this medication then your blood work would have came back as abnormal as well.
Since you are having no other signs of any illness at this point, I would just monitor your temperature daily. Morning, Noon and night. Try to do this the same time. If it continues to run a normal pattern then they may just be your normal now. Which then would explain all the blood work coming back fine. If there is a different temp each day and no normal pattern, then you should see an endocrinologist which would be more helpful. (if you do see an endo, make sure to get a copy of your current blood work so he has something to compare it to)
Hope this helps Hun.