Not sure??

So my 8 year old told me today that a group in her grade have been picking on her a number of times, I want to believe her so I can help her out but in previous occasions she has not spoken the truth.

I don’t want to go in and speak to the teacher about it and make a complete foul out of her and myself, but I also don’t want to ignore it she be telling the truth and have it get worse and out of hand

What do I do? Do I believe her or do I drop it