Advice, Please?

I received a call at home today from the House Supervisor. Apparently, a patient complained that I "came into her room, gave her a shot, and just left without saying a word". She is now complaining of weakness in her legs and generally "not feeling good" since she received the shot. I'm baffled because I feel like I'm dealing with a "guilty until proven innocent" situation here.

This patient is partially blind, a diabetic, with chronic anemia related to chronic kidney disease. Her blood sugar was below 100, with no orders to give regularly scheduled insulin (only a sliding scale was ordered). She wasn't confused when I took care of her, just soft-spoken and maybe a little tired.

I didn't give her any shot; not insulin or anything else. I gave her blood pressure medications and a Nitrobid patch (of which I read out loud and told her what they were for). Her sister (who is equally blind; she couldn't see what was on the TV and I know because I commented on the show they were watching) was in the room and stated that she saw me come in, heard the patient say "Ow" then watched me leave without saying a word.

A few things about this bothers me (besides the obvious fact that I didn't administer the shot), among them being that I always tell patients what they're getting and why as I open them, because it's the safe way to do things. Also, it's a pain to have to pick out the one pill they didn't want from the cupful. I always ask them if I can get them anything/ if everything is okay before I leave the room because it's a pain to just run back in if they press the call light.

The Supervisor told me they didn't see a needle in my hand, nor did they see anything dispensed from the Pyxis or documented in the eMAR. But the sister is sure they saw me randomly come in, walk over to the patient's side, administer a shot, and leave without acknowledging them. Typically, nurses are only called on their off day if the patient was in serious distress as a result of a nurse's actions or if the family was extremely upset. But! "It feels like a bizarre situation, so don't worry about it. It's been resolved."

Well, I'm worried. Why call (in the late afternoon) and ask after investigating if there is nothing to worry about? I was told that the patient was in no danger, nor is she in any distress at the time of the call (only feeling a little weak in the legs). How was this resolved, because obviously there must be reason for the patient's sudden weakness? I feel like this is going to be a case of them taking the patient's word over mine scenario. Of course, the management will take nurses aside and "coach" them for every little patient complaint.

I don't know if I ought to be to worried about it though, which is why I'm posing this situation to you good people. Some words of advice from the more seasoned nurses, please? Thanks in advance!