Water from my electric toothbrush shot up my nose. should i be concerned about amoebas? can anything treat amoebas if they're in someone's nose?

No worry: Unless you were using pond water to brush your teeth in there shouldn't be an amoebas on your toothbrush. You are no more likely to get amoebas in your nose than in your mouth when brushing your teeth. So if you were using tap water or bottled water or boiled water while camping you are alright.

Very uncommon: THere are antibiotics for amoebas but we don't give them unless there's a problem Without an actual examination, I cannot give specific medical advice on your particular health

Amoebas: Who has the amoebas.?? If you do not have, and have no immune disease, squirting water up your nose- even if contaminated with something, is unlikely to cause harm or disease. Possible: Blow your nose, consider squirting some few cc normal saline in each nostril to encourage flow and be well.

Not a problem: You are concerned so use a Neti pot and "flush" your nose and sinus with saline (salt) rinse or get Ocean saline spray to use in your nostrils.

Stop worrying: That's why municipal water supplies are chlorinated, to control pathogens. If you are worried about your water supply, have it tested by a lab. If you are worried about your WaterPik, clean it. If you are worried about your nose, don't be.