My 1 Year Old Has Been Sleeping And Crying All

My 1 year old has been sleeping and crying all afternoon, like an in pain cry. I thought maybe a sore throat bc I had one yesterday but it lasted less than 24 hours. I gave her some milk and a few bites of oatmeal about an hour ago and she threw it all up. I'm starting to think it's her tummy. I did realize the last thing she ate before the crying spells began was a 4oz baby yogurt, which she's had before and I checked the date and it was fine. The only stool she's had today is 2 small very hard poops in one diaper. Is it possible it's just bad constipation?