The issue isn't the amount of photos you have, it's Photobucket being money grabbing b@st@rds.
They have changed their T&Cs to block all 3rd party hosting unless you pay for the highest level account from them.
There has been a lot of discussion about this on the various forums I use.
All is not quite lost for old threads, the pictures can still be accessed if you right click and open in a new tab, they just don't show as part of the thread anymore.
Unfortunately unless they go back on this decision nothing is likely to sort this out in the near future.
I have now started to use http://www.imgur.com
to host my pictures instead and have advised all users of the cub forum I help run to do the same. I won't be sorting all my old threads, but anything new I post anywhere will not be via Photobucket.