Portia and her phobia moments

Lately Portia has been driving us somewhat insane. I mean she's still adorable funny, smart as a whip, etc. But she has taken up being concerned about things killing her. Here's what I mean and it's been happening about 5,000 times a day:
"Mommy, Keiko breathed some of her germs on me. Am I ok?"
"Yes, Portia you're ok."
"Mommy" Mercedes' sleeve touched my arm. Am I going to catch on fire?"
"No Portia you're not going to catch on fire. You're ok. Stop worrying" I then explain what it takes to start a fire.
"Mommy, I breathed in a smoker (translation: someone was smoking and she breathed in the second-hand smoke out on a walk or something). Am I going to be ok?"
Yes Portia you will be fine Sweetie. Why are you so worried?"
"Well I just want to know if I will be ok."
"Yes Portia you will be fine"
"But Mommy is my nose going to catch on fire because I breathed in a smoker?"
"Portia is your nose on fire now?"
"No Mommy"
"You will be fine Portia. Your nose can't catch on fire from breathing that in."
"Mommy I looked at the sun. Am I going to be ok."
"Yes Portia you're going to be fine. But try not to do it on purpose"
Ohhhhhh Mommy I looked at the sun again on accident. Am I going to be ok?"
*sigh* "Yes Portia you will be fine".
~It's non-stop~
And then there is the night time when her imagination comes alive.
"Mommy" (in a little whisper right next to my ear at 3 am) I dreamed a lion was getting me. Can lions get me Mommy? Can they smell me?"
"No Portia. Lions live in Africa. That is very far away. They cannot get you and it's too far to smell you. You're ok. You are safe."
She climbs into our bed for a few hours until I am awake enough from her moving to take her back to bed.
~next night~
"Mommy!" (an urgent whisper into my ear and dreams again in the middle of the night) can my dreams become real?" I know where this one is coming from...a movie she saw.
"No Portia your dreams won't become real. You're ok. You are safe. I love you."
"Are you sure Mommy?"
"Yes darling I'm sure now go to sleep" Again she crawls into our bed until Shaun or I are awake enough to take her to her bed.
~3 months of this so far~ day and night.
But they are legitimate fears in her world. We have been trying to trace it back to where it started. And we were teaching the girls about the symbols on containers (like a bleach container). Some have a corrosive symbol, others have explosive symbols etc. And we think that's where it started. But we didn't teach it too them in a way to make them freak out. It's interesting how she reacted though. I have caught myself, lately, watching my warnings to her about things though. And I nearly lose it when other people warn her (even teasing) Like the other day she was playing a game on my i-phone and someone said "That's going to wrought you're brain". They were teasing but she took it very literally and almost lost it over that comment. It's just interesting what she takes literally and really worries herself over.
She was in Shaun's truck a few weeks back and her had brushed a windshield wiper fluid container and she FREAKED! "Am I going to be ok Daddy?" She was wailing...and really terrified because she saw a symbol on the container.
We try not to get impatient and brush her off. But some days it's very frustrating. Sometimes my answers have been through clenched teeth. I do have to say in the last week it's started to lessen. And that is a relief. We have also injected humor lately and that seems to work well sometimes.