6 year old with blood in knickers

[Mojavewonderer]

I took my 6 year old daughter to hospital yesterday with a suspected UTI because she had blood in her knickers and was complaining of a sore tummy. Her urine was negative, no temperature or clenching of the muscles when the doctor palpitated her tummy. She looks healthy and is otherwise fine so the doctor couldn't explain the blood in her knickers. She is bleeding from somewhere down below but the doctor said she didn't want to examine her now if she was fine which I think is fair enough. She said if the bleeding carries on then to make an appointment with her GP and get it checked out. She still is bleeding but no pain, it's not much but enough to show up in her knickers which I am changing constantly because she won't wear even the smallest of pads.
Has anyone any idea what the bleeding could be? The doctor said she could have scratched herself but I have watched her and she hasn't been scratching herself down there. I asked the doctor if it could be a period but she said unlikely. I am at a loss to what it could be and I am very worried. I will make an appointment first thing tomorrow but a bit of reassurance would be nice please.
She is not on any medication and apart from being ASD there is nothing else wrong with her.

Could she have torn her hymen while excercising/gynnastics etc?

Could she have put something up there? That is quite common in younger children. I am thinking maybe a bead or crayon?

Did the dr check her anus to see if she had a wee tear? Periods at 6 are uncommon but not unheard of.

The doctor didn't examine her private parts because she said she wasn't worried when she was not showing any signs of illness. She is still staining her knickers though which is obviously not normal.
She is very private about her bits. She doesn't even like me seeing her naked. I was the same at her age apparently.
I have no idea if she has inserted anything in her vagina but it's a possibility. I will definitely be making her a doctors appointment tomorrow, I need to get to the bottom of this as I am really worried.

I cut my vulva at a similar age, climbing on a wall. Didn't realise till saw blood in my knickers and told my mum. Any chance of something like that?

It's possible, I asked her if she is sore and she said no. It's quite hard to get her to tell me things because she doesn't always understand.

How much blood are we talking? It is a smear or a good few drops?

Oh wee soul, really hope you find a cause and put your mind at rest x

Hi did you ever get to the bottom of your daughters issue? I have 6 years old with same problem and I'm very scared. Please let me know how you got on positively.