Baby got food poisoning from sweet potatoes?

8 mo dd has had sweet potatoes before that I've made and jarred stuff and had no problems. The latest batch of sweet potatoes I made at home, made her vomit. No diarrhea. And really vomit - everything she'd eaten came up for several hours. The first time it happened I didn't make the connection - she ate 3 cubes of it and puked the entire night. I thought it was a virus or something. A week later, she just ate a few teaspoons (thankfully she wasn't very hungry) and puked 3 times.

My question is about my food prep -
I steamed them in their skins for about 40-50mins (longer than usual cause I forgot about them).
Should I have peeled them first? I mean I thought perhaps bacteria could be on the skin?

I'm very careful about washing my icecube trays in hot soapy water. Other than the steamer I used, I used a spoon clean out of the dishwasher. I'm at a loss at how this could have happened.

Anyone heard of bad batches of sweet potatoes? I bought the organic ones from Whole Foods. I've made apples, pears, quinoa without any problems.