Is is ok to use slightly sour curd for chicken marination?

The last time I used slightly sour commercial curd (it usually isn’t sour and was well within the expiry date) for marinating chicken. An hour or so after cooking, there were little bubbles bubbling up to the top of the curry, and I had stomach trouble after eating the chicken. But I wasnt sure if it was the curd or whether the shop owner had left the chicken at room temperature for too long or whether it was because the shop was just unhygenic.

This time too, the curd is slightly sour and I just wanted to know if it is considered safe to use slightly sour curd for marination. Or does the sourness indicate that that it has too much acid or that the curd has got spoilt and can be bad for the meat?

Update: Slightly sour curd (it’s not supposed to be sour) did create a slightly sour taste in the cooked chicken, but it got masked to a reasonable extent by the spices, salt and onion flavour. The little bubbles are just a normal phenomenon I’ve observed even if I cook without marinating in curd. After cooking with slightly sour curd a few times, I could conclude that it is ok to use it.