Hello,
Great, 6 inches from the bulb is fine, she should be getting plenty of UVB. What sized feeders did you feed her, were they wider than the space between the eyes?
I don't think it would be parasites hitting this quickly though. Since you mentioned it didn't happen until you fed crickets, it sounds like the crickets may have been too large. She could be impacted & unable to pass them. Twitching on the stomach is a sign of impaction.
For now, I would feed softer foods such as canned or fresh pumpkin, or sugar free applesauce, mixed with squash baby food or fresh pureed squash with a drop or two of olive or coconut oil. Give with a plastic syringe or dropper to help things move through.
You can also give her a daily
bath, while massaging on the right side starting underneath of the arm pit area in circular motions down towards the vent, gently.
Let us know how she is doing.
Tracie