I have worked with several of this type of personality. I think most of it is to cover up with their inadequacies. (Psychobabble)
The worst I ever worked with was about 13 yrs. ago. Madelyn was new to our unit. She was an RN, I was an LPN. I worked nights while I was going to school for my RN one summer. This chick (my pet name for people who pis# me off) starts telling me what to do. Only everytime she opens her mouth something else screwy comes out. Ex: She was watching me change a dressing. (now mind you--I had been working on this unit for 4 yrs by now) and she started to criticize my technique. She tried to tell me that you put the moist dressing on the intact skin, and the dry dsg on the wound!!!! Well then and there I knew she was swimming in the shallow end of the gene pool.
One night several weeks later, I again had the pleasure of working with this ditz again. I had pretty much stayed away from her. She was busy, so I answered one of her call lights. The frail gentlemen that was in the bed was very apologetic. He had spilled his water pitcher and wondered if I could change his wet sheets. I knew that his family had brought him in for abx treatment for resp. inf. He had terminal Ca, but there was no indication that he was going to hit the eternal road on this admission.
So anyway, flighty nurse comes in, turns all the LIGHTS on. Then proceeds to take over my changing of the bed. Fine--but then I hear her say to this tired gentlemen (who only had spilled water), "OK let's give you a bath." He stated he did not want a bath. She told him he did not know what was best for him. I was very angry by now. I pulled her aside as she was getting towels, washclothes, razors etc. I very calmly explained that all he had done was spill his water pitcher.
She looked at me and said that he needed to be clean for when he leaves.
I thought, hey maybe he is going to be discharged in morning--and she knew something I didn't. So I continued on my rounds.
Not 3 minutes later I hear "So Mr. Soandso what do you want to do before you die???" Then to make matters worse I hear him say, "Why, am I going to die?"
I did not hang around for more of the "theraputic' talk she was giving him. I went directly to my DON--I did not pass go or collect 200$ (which incidently was my full time pay for a week). Madelyn lasted about 2 more weeks on our floor, when she made a nasty drug error. She quit and went into home care.
Sorry this became so long. Anyway--I haven't run into anyone as bad as her since, but when I do work with that type of "I know it all" personality, most times I steer clear. If that is not possible I will politely smile and walk away--then do my own thing. THese people like to get under your skin--they are like animals they can smell uncertainty and lack of assertiveness. All I can say to you is explain that you went to school and that you were so intelligent that you passed your boards. So thank you for your advice I will take it into consideration. (Even If you were a CNA you still had to take a class and pass it).
Don't know if this will help--but hopefully this person does not practice nursing with the lack of ability that Madelyn did.