Hi .
It's not uncommon to become unresponsive to treatments. You need to contact your IBD team and let them know so that they can try another treatment for you.
As above, Pred is not for long term use anyway. It may be a simple case of being able to increase the medication you are currently on, but if not, there are lots of different options available. You probably won't need another colonscopy if bloods and/or stool samples show inflammation. And in all fairness, your team may just take your word for it based on your symptoms and start something new before the results were even back. My team always did.
Good luck!
- Sahara (team member)