You're right Veronikkamarrz, good you're so observant, your gerbil does seem to be in some kind of pain and distress, can be a number of things which is why a vet really needs to look at her asap.
Meanwhile, (unrelated tip) it's best you remove the wheel because these have proved hazardous for gerbils unless the design is such that the tail cannot possibly get caught. Wheels (fine for hamsters) have caused nasty accidents for gerbils, sometimes even skinning the tail, ouch! You can't always rely on pet shops to be good about this point.
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avatar photo caption: The Red Sea by Eilat