Did I Eat Some Bad Yogurt ?

So I brought a box of yogurt from the store because i Love yogurt it was variety blueberry peach and strawberry this was about a week ago. and i put a strawberry one in the freezer to freeze it and forgot about it last night i took it out and put it in the refridge to unthaw and i just ate it like 5 or 10 mins ago it was watery but i mixed it up and it tasted a little sour now my stomach is like hurting Real bad and feels kinds bubbly and i have a bad headache DID I EAT SOME BAD YOGURT ? Pleasee Helpp and dont post anything stupid thankss (: Oh and the yogurt was pink so i couldnt really tell if it was spoiled but it did look a lil grayishh too