It's probably the light. It's too much coincidence that this happened exactly when you got the new bulb. Several people on here have gone through exactly what you're going through now.
But it's possible it's something else. That's a fact that can't be ignored. Give it a couple of days and see what develops. If they start showing other symptoms - particularly breathing with the mouth open, yawning, swimming lopsided - then we'll see. In the meantime, just keep them warm, feed them as usual, and keep using that heat light.




