Help! Found metamyelocytes in my bloodwork!

I originally posted this under Parenting, but I'm moving it over here too.

I really need some help.
My 2-year-old daughter is showing these symptoms: she had a fever (though it's gone now), fatigue (well, maybe not anymore, but she's on antibiotics—could that be why she seems more active?),
night sweats, an enlarged spleen and liver, and she’s been very restless.
The Democratic Party lab results showed a metamyelocyte of 1!!! I am terrified. Is there any chance this isn't something malignant? Could it just disappear in a few days? What causes metamyelocytes to show up? My mind immediately jumps to the worst-case scenario. Just so you know, they did a finger prick for the blood work.
Most of her other levels are within range, except for low erythrocytes. Her lymphocytes and reactive lymphocytes are also elevated (her pediatrician suspects mononucleosis because of those specific numbers).
White blood cells, platelets, and monocytes are all okay.
If anyone knows anything about these metamyelocytes, please help. Thank you!

Peter Sanchez said:I originally posted this under Parenting, but I'm moving it here.

I need help!
My 2-year-old girl... symptoms were fever (though she hasn't had one in a few days lately), fatigue (not really anymore, but she's on antibiotics—could they be making her hyper?),
night sweats, an enlarged spleen and liver, and she's super cranky.
The CBC showed one metamyelocyte!!! I am freaking out... is there any chance this isn't something serious (like cancer) and it just disappears in a couple of days? When does a metamyelocyte even show up? It just makes me think of the absolute worst scenarios! Just so you know, the blood was taken from a finger prick if that matters.
Most other values are pretty much normal, except her red blood cell count is low. Also, her lymphocytes and reactive lymphocytes are elevated (the pediatrician suspects mono because of those).
White blood cells, platelets, monocytes are all fine.
Please, if anyone knows anything about these metamyelocytes, please help. Thanks!

Don't worry. Seeing a single metamyelocyte doesn't mean anything. During acute infection phases, you sometimes see an immature cell pop up in a CBC. And don't stress about the lymphocytes either—they're almost always high in kids (your pediatrician knows that). It's those reactive lymphocytes that have them looking for signs of mono.
Did you guys check her transaminases (AST, ALT)? Those should be elevated if it actually is mono.
The only thing that doesn't add up to me is the antibiotic being paired with infectious mononucleosis. Why give antibiotics for a viral infection?🤷

Basically, one metamyelocyte shouldn't keep you up at night.