This is a problem I need help with ASAP

First you say you only bought the dlc, then you say you've bought the collection..

So what did you bought?

If that process has not worked please check the enforcement site for current status of you ban. If you do not see any active bans there's been an issue with the enforcement site not showing additional enforcement actions and the only way to see if you are
still under a ban is to call support by phone and have them check for any bans. They can not tell you why but if you have one and when it will expire

also you can try to clear system cash by going to memory hit Y and it will give you options (like clear system cash) or what for the next system update witch should fix the problem

Your avatar and gamerscore shows up correctly on xbox.com, so the problem seems to be local. is your profile stored on the HDD or a flash drive? If you haven't already, try resetting your xbox too just to see if it comes back normally.

From what I've seen before, there is a chance your profile has been corrupted. If clearing your cache doesnt fix the problem, delete the profile (do not delete items tied to the profile) and the select recover/download profile. This will get your account
from the servers and store it onto your console again.