Leopard gecko's odd behavior

I got my leopard gecko a month ago. I love her to bits, her name’s Frankie. The vet said she was around 6 months old. Maybe I’m just worrying too much, but I figured I should get input anyway.

To begin, I have a hot side and cool side in the tank; the hot side is 87 °F and the cool side is 70 °F. The hot side is powered by a heat lamp, which also powers the heat mat underneath because otherwise it can’t maintain its heat. The substrate is reptile carpet, which I clean at the end of the week together with all of her hideouts and the whole tank. I feed her 3 crickets every day and I switch between calcium spray and multivitamin. As for calcium, she also has a powder in a bowl to eat whenever she needs it. I also have a UVB light set up that I put on during the day so she can bask.

She’s a weird one; she’s constipated and it worries me. I feel like she doesn’t defecate as much as a leopard gecko should, and when she does it does have its white and brown component and it looks like a literal bean. It’s also a bit wet. Unfortunately, she seems to always defecate whenever I’m not around, so it gets dried out by the heat lamp and therefore can’t be tested; also her defecations are so rare; I’ll try and get a sample this weekend if she does. In addition, she sometimes makes noises out of the blue. I know leopard geckos are capable of doing so, but with that and the constipation, something seems off. She’s also an unstable walker. Yes, she can run, but when she walks slowly, it’s always very shaky. Today she had a head spasm for a few seconds and that worried me even more. I wonder, maybe she was swallowing? This happened after eating, but the crickets are pretty small.

She eats regularly. Sometimes I see her drinking water. Although today when I finished feeding her, she tried lunging for a rock. She bit it too, and when I took them away, she kept looking at them as I moved them back and forth. I did this to test if they were interesting to her and they were. So no more rocks in the tank. I then changed her water and after putting in ReptiSafe®, she looked at the bottle the same way she looked at the rocks. I think she wanted to eat that too.

I took her to the vet on Monday. After an exam (which consisted of looking at her stomach for signs of impaction, her gums, and her eyes) she was fine, however her feces couldn’t be tested since they’d dried out. The vet said (at least for the constipation issue) to use a UVB light (which I had just started) and to maybe try a bath. I know that Frankie will hate it; she doesn’t like me holding her.

This was… a lot.

The question: why is she constipated and what can I do?

Ever since I started the UVB light, I feel like her constipation’s gotten worse. It’s been a week since she’s defecated.