Health lowering but no disease in my active effects

My health was at 175, now it's at 150. I have not changed armor or necklaces. If I go to a temple and get a blessing, my health goes back to 175. But then it will drop back down again after a day or two. And under my active effects it's not showing any diseases. Does anyone know what is going on?

I'm playing on the Xbox 360.

It sounds like Fortify Health where your health is temporarily boosted thanks to enchantments/effects of equipment and potions

Fortify Health is an enchantment and an alchemical effect that temporarily increases the maximum health for a limited time.

This would explain why your health is boosted but then after a while it drops. Salvaged/bought Fortify Health Potions normally have the effect last for 60 seconds.

There is a Blessing of Arkay which

Increases your health by 25 points.

Which would explain it and your health is dropping by 25 points because the blessing has worn off. if you keep an eye on the time you should notice the change after eight real-time hours of gameplay. if you check the Active Effects category of your Spells Menu you should see "Blessing of Arkay" there