Betadine would be best to clean it. Drug stores carry it.If it stinks it needs a good flushing out. It’s got to be full of bacteria and it looks like it’s been there a few days by the pictures. I’d pack it with neosporin after flushing it out. Warm salt water would help to wash it if you don’t have anything else. I’d also start her on some antibiotics ASAP. It’s a good thing it’s winter or it might have gotten worse pretty fast.