The dosages of a multi are usually very low. Very few of the vitamins have any over dosage problems. There used to be a concern for B-12 overdoses but that is not a concern any more. If you look at the minimum dosage sizes you can buy each vitamin or supplement in, you will see that the manufacturers are within the dosage ranges I have mentioned.

Magnesium needs to be combined with calcium. Some calcium comes with magnesium already combined. I don't know if the lip cracking is related. Never heard of that before.

Have her eyes settled down? Nystagmus is a symptoms that is common to PCS.

Have you or she tracked her symptoms with her cycle? The ups and downs of hormones may be related. I've been reading about progesterone. Its neuro-protective value is interesting. It surges the two weeks before a woman's period. The other two weeks could be more symptomatic. Just another thing to consider.

From what I see on this forum, it appears that teenage girls have more PCS struggles. Could their body's changes be part of the difference? Worth considering.

My best to you and her.