I got a baby beardie for Christmas, and all has been pretty good since then, but she has been acting very strange lately. She has a styrofoam Rock wall in her tank that she always hides on top of. When she is in her tank, she get so dark, her underside is pretty much grey!
<<<< I think perhaps without seeing her and the tank and lighting setup she's getting too cold.
Likely reasons
=== I assume you have one of those modified fish tanks so common in the USA which comes with a mesh screen top ==> mesh / screen tops are not good as they do nothing to hold the warm in the terrarium where you and your hatchling need it, basically warm air created by the basking globe is very buoyant and rises being lost immediately through the screen / mesh , this makes it very hard to maintain a good stable thermal air circulation and thermal gradient in the tank,
=== easily fixed by removing the mesh/screen top and replacing it with a solid timber (1/2in thick plywood is excellent and many hardware shops will arrange precutting for a small fee to your specs) ,the solid timber top will do the following :
--- it will insulate the tank from outside conditions
--- it will force the warmed air inside the tank to circulate creating a nice stable gradient
--- it will mean you don't need as many watts in the basking globe to achieve the same basking spot and warm zone temperatures
--- it will be animal proof (other pets)
--- it will provide an excellent mounting platform from which to mount the UV light fixture and basking light and CHE fixture (if you are using one) , all can be fixed / mounted under the "lid"
Then when I take her out with much difficulty (I try to handle her everyday, yet she still doesn't really seem to like me
as she runs away every time I touch her) she brightens up quickly.
<<<< she's not sure if she likes being handled yet or if she really trusts you, this will come with time and patience. I find a great way to build a strong / trusting relationships with a lizard is to handfeed it some of it's live insects daily while nursing and petting it and talking quietly and calmy and reassuringly to it . ie with Peppa and Toothless initially I restricted handling to a maybe 5-10min per day and made a ritual and routine of getting them out first thing before feeding them, placing them into small tub while I spot cleaned and caught any remaining hiding crickets , then I'd lift them out place them on my chest so they are facing me, and I'd have 2 - 3 crickets ready with their heads squashed (to immobilize them and make some cricket inards come out, I'd pull off a hopper leg and have the cricket inbetween my finger tips while I slipped the thick end of "drumstick" between the hatchling's side lips (side is easier as they see the food item, and it's easier to slip it through the lips and teeth there) when hatchling is chewing the "drumstick" / timing is important I'd present the head end of the cricket to the side of the mouth and usually it's eaten promptly by the hatchling, repeat this for each of "bonding" insects , then I'd gently deposit the hatchling back into it's tank and give it 3 - 4 crickets at a time so I don't overwhelm it.
I found they both liked small (mealworm sized) silkworms and only needed place the worm on my shirt where they could see and reach it and it usually promptly disappeared into their mouth. Nom nom nom ...!
On the top of her wall, there's not much room to strectch up, so she just lays flat, but then on her rock, she does the same thing, and just looks sad. She normally puts her head up.
<<< normal behaviour Also, sometimes when I hold her she will be still for ages, then quickly tries to 'escape' .
<<<< normal for a hatchling, she's more likely spotted something she wants to explore or investigate , if you place her on your tummy /chest within the weight of the left wrist resting on the think part of her tail this will "discourage her from suddenly leaping off/dashing off , thing with very young hatchlings is they only have two speeds = stop and warp10.
She has taken a few tiny falls, but still seems ok physically.
<<< how far onto what ? is best to only hold the hatchling when you sitting on the bed, on the floor, or on a nice soft lounge , this way if they take a fall it's not very far and onto a surface with some give in it , best not to walk about with beardies on the shoulder, chest, top of the your head , as they can move fast and will land hard (often on a hard unforgiving floor surface and this has the real potential to cause serious injuries to them. I'm sorry if all of this is gibberish, but I'm just trying to include all the details. I just want to look after her properly!