Intentional or unintentional sexual thoughts

I've been restless for these past few days. Once I have an unappropiate thought about a holy figure, and I think it was unintentional (not sure though). But then I kept thinking about it over and over again (I tried to analyse whether it is intentional or not). My questions are: 1. Is sexual thought about holy figures unforgivable sin? 2. Am I creating bad karma by thinking about it over and over again? 3. What advice do you have for me? I keep on feeling really guilty and keep on thinking about it.