I personally have decided I will never give please, except if a close friend/ family member needed it.
A while back, an older friend of mine (young,fit and healthy) went and gave blood.
I was at his house the time this happened...
As he got home he noticed he wasn't feeling well and was dizzy. He had obey all recommendations they told him..
Went to go to the toilet then faints on the spot, cracked his head HARD on the toilet. Required several stitches on his head. He had horrific concussion for several days.
With your daughter, the most concerning thing is the black cloud comment, but one wonder's if she is being a bit dramatic, deliberately, cause that's a sort of stereotypical depression idea.
I have been told if you have an infection and give blood the infection can come out stronger or develop, because your immune system and fighting ability is down.
She might be depressed though. Please consult an expert.
Depression lasts at LEAST 2 weeks (should be a fair bit longer usually).
Some symptoms include, excessive sleeping or inability to sleep (especially waking early, can't get back to sleep).
Strong loss of appetite (in some cases opposite)
Negative mood for at least 2 weeks, the majority of the time.
May cry easy or feel like crying but not be able to.
Often (not always) energy level is very low, may be slowed down.
Loss of interest in things they usually enjoy, don't enjoy things.
In strong cases, a person may seem detached, avoid talking to others, not make eye contact, never show any genuine positive emotions, smile etc.
Danger signs of suicide include:
Comments of the nature "people would be better off without me"
Sometimes morbid "sarcastic" jokes about if they were dead.
Self Harm, cutting, any form of self harm.
Strong comments indicating low self worth in conjunction with any of above.
Disinterest in things such as possessions, future events etc.