Breath holding spells

My 2 year old daughter, when she is in pain of is upset and cries, cries for a few seconds and then stops, holds her breath until she passes out completely. She is like a ragdoll, when she is unconscious is not breathing at all and we have to splash water in her face to wake her up. We tried to ignore it, like other websites suggested it (like the child wants attention) but my daughter still wasn't breathing and had to wake her up.
We are struggling, the kids have no insurance, but I don't know if it is worth going to the ER with it or not. We can't pay a doctor, but it is very frightening to watch her not breathing with each episodes.
She started this when she was a baby, when she didn't get her formula in time and got angry, but after a month or two she stopped this behavior. About 2-3 months ago she started it again with the passing out episode, but I can remember that she had a big bump on her forehead. She fell on my mom-in-laws tile floor. I don't know if that may be a link or not. We did not take her to have it checked out, she was behaving normally, she was not sick at all from the fall.
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But these breath holding spells are happening almost on an every day basis, after we wake her up she is very tired, she sits in my lap for an hour or so very pale, then about an hour and a half later she returns playing.
I very appreciate your help!
Thank you