One of my family members were amitted to the hospital for a sore and turned out to be a staff infection/mrsa and got into her blood stream. She didn't tell us at the time what she had only that it was an infection in her blood while she was in the hospital I noticed my daughter has been acting differenyt than normal she has been very fussy and seemed tired a lot more often but would fight her sleep. Then she has started to throw up a lot more often after every feeding I gave her tylonal and two hours later er temp. Was 99.4 (my daughter is 3months old) I took er to the hospital and told them what was going on and mentioned that the family member was amittred to the same hospital I was at for an infection in her blood theyseeemed concerned and asked further questions about the family member but that was all I knew. So they didn't think that was it si they gave my daughter a chest x-ray an ultrasound along with a sample of her pee they couldn't find anything wrong. What should I do?

Your daughter should have a regular pediatrician, and you should not be using the ER for this, although your concern is understandable. When the ER staff looked into the situation of the MRSA, they decided that it wasn't connected. They did more than the usual number of tests on a 3 month old who is vomiting and has a very slight fever (99.4 isn't really a fever). In fact I wouldn't even give her Tylenol that quickly. Tylenol isn't for fussy, tired, and vomiting. She needs her regular doctor. If you don't have one, get one. Most hospitals have an associated clinic.
What are you feeding her? Is she getting enough water in the summer heat?

Regarding infections like MRSA: they are caused by bacteria which get under the skin through a cut or bite. Those bacteria are everywhere on us, and it's just a matter of our body's ability to fend them off. There's no reason to think that you or your daughter will 'catch' MRSA. Your daughter might have a typical stomach virus, which you would treat with clear liquid diet, but I'm not here to diagnose, just offer suggestions.

I agree, child needs to go to their doctor, not ER, ER is not place for regular and normal medical care.