9 month old baby constantly presses on her belly. ~2 month duration. Has mildly elevated liver enzymes. Seems slightly fatigued. Mono?

Needs face to face.. evaluation.Mono isn't common in babies as young as yours, however it's not impossible.Regardless, this needs a face to face eval by the pediatrician to look into. Certainly growth spurts can alter a babies energy levels and even mild illnesses can cause mild elevations in LFTs, but your doc needs to make sure that there is nothing else to worry about.Steer clear of acetaminophen until followup!!
Hard to say. There are many enzyme studies that will read high id adult standards are used but just reflect normal in kids. If truly up, they can go there during many simple childhood viral illnesses, including mono, many tire during illness. If you have concerns discuss with your doc. Mono tests can be negative in the early months of true mono and may never turn positive,but an EB viral study might confirm it.