Help! I think my 15 month old ate gone off steak😭

[Lilmizmiz]

Right so I made well done steak for her last night and there was still half left so I just put it in a thin plastic bag (with its original packaging) tied a knot and put in the fridge thinking im make it again the night after with rice, initially it looked like it was going darker but only around the edges I just thought it’s because it wasn’t air tight stored so being exposed just darkened the the outside as inside was still red - smelt it and was fine - I made it and started giving it to her she had about half of a medium slice and then I tried it just because I overcooked the outside and didn’t want to put it to waste, straight away I could taste it was so sour I immediately stopped giving it and made my husband try it as well he confirmed then smelt the bit that was uncooked in the packet and said it even smells sour but to me I expected gone off meat to smell really bad not sour! Now I’m panicking as she already has diarrhoea from teething and I don’t know how this will effect her please any advice or anyone experienced similar

If you cooked it well done you will likely have killed off any bacteria. Fingers crossed she's ok.

Just up the fluids, give jelly, watermelon stuff with lots of fluid in it. Will also soothe the gums.
Ride the storm as long as there’s wet nappies and little one is ok, playing aware etc. just keep an eye.
There’s always 111 at the end of the phone if she starts to become unwell.