Elevated white blood cells in discharge?!

32 weeks pregnant and went to the bathroom with some randomly bright red spot when I wiped. It only happened that one time I wiped and then it went away. Doctor told me to come in and get checked. She did an exam and said she thinks it was my cervix irritated because I had sex the night before. She did a swab to put under microscope to make sure it wasn’t anything else like yeast infection or bacteria. She said my discharge looked normal and so did my vagina and the test looked fine as far as yeast and bacteria BUT my white blood cells were up. She gave me a z pac and sent me on my way. Has anybody else had something similar happen or go through this? Really nervous as to what this could be and why?! I haven’t had any symptoms. Just really depressed about it and am thinking the worst. Thanks in advance for anyone who shares what they think and their story.