Traffic consistently DROPPING - Help please

Converted from phpbb to vbulletin and SE traffic has consistently been on the decline since instalation, please help stop the bleeding.

vBulletin 3.6.8
vbseo 3.1
Sitemap Gen 2.1

I have now completetly dropped off of the map with google for my top keyword, and yahoo has slipped

Before Nov 16th - position 9
Today Nov 30th - position 100+

This post may have alot to do with it, but please any advice is welcome.

Thanks

If you only installed vBSEO on 16th November this is to be expected.

All your URLS are being changed into a friendly format, one that Spiders will love. However not even Houdini could manage that over night. Leave it at least 4 weeks and start watching it creep back up.

A phpBB to vBulletin change is more significant. However, you do have history with Google, so they will re-index. Check your sitemap and make sure that it running. Verify the crawler activity to ensure that the search engines are visiting. From there, it will be some waiting, but you will recover.

Note: Check which of your old pages were generating the best traffic. Determine those URLs and setup custom htaccess redirects to send the search engines to the new location of those particular files. This will help "stop the bleeding".

Give it a solid month before you start losing your mind it takes google a little while to re-index you

You could always set some redirects in vbseo
oldurl => newurl