This happens to people, I'm sorry to say, because they rank up into too high a pit level. To mitigate it, stay where you're at until you can level/skill/gear/promo more.
When I played s1, I stopped ranking higher into the next level pit to keep my expo at a reasonable difficulty level. Not too hard and not too easy. Learned it the hard way because my original server is 10. I hope this will help u some.
Oh! Be wary during contests. It will mess with pit, crypt, expo. Idk about colli.