If no new main quest has appeared then do this.
Enter each building in each town you can find and talk to all the people.
Now check all the quests to see if a new main one has appeared.
If no new one has appeared then try the top quests in each town to find out if a story scene starts possibly.
If there is still no new quest then do a side quest. Sometimes this has to be done before you can progress again. In fact in a few quests this is completely true.