Very Concerned if N Fowleri. Infection?

I have a borewell underground water connection through jet pump that is stored in tank kept on terrace. I am very anxious since I have read about N Fowleri infection. I was taking a bath when a little water went in my nostril while washing hair. I tried to blow it out covering my nose with a towel. It didn't go up my nose. My concern is that since I blew my nose too hard, can the water be sucked up till my sinus, as I had read that on blowing nose hard, phlegm present in nose can get sucked in sinus due to the pressure difference thus created? Am I safe? We use RO water for drinking, and we use tank water (pulled up via jet pump) for washing face/bathing etc.  Please help me relieve my worry as I have to look after my family, I cannot risk on my life. Can I take Azithromycin to prevent infection?