Not sure if this is the right forum, apologies if it isn't.

I returned to Caius Cosades after having completed the Antabolis Informant quest but when asked about Orders he responds that I need to find Sul Mattul and speak with her. The Antabolis quest won't end, and I don't have a Sul Mattul quest in my journal. Can anyone help me with this problem?

Did you return the box to Antabolis and get his notes? If you don't pick the correct topic you may not get them.

This is odd because the Sul Mattul quest is later. What MQ have you done.

I did, I have the notes on the Sixth House. Were there other notes I should have?

I'm sorry, but what are MQ?

I'm beginning to suspect that I'll need to use the console to fix this. Anyone know of some commands that could help?

MQ=Main Quest.

You should also have some info on the Nerevarine cult.

Anyway, Journal A1_2_AntabolisInformant 20

For future reference, you can get all the quest info you need here:
http://www.uesp.net/wiki/Morrowind:Quests

The quest is now complete, but Cosades says the same thing. I may as well just skip the intermediate quests, but thanks for the help.