it's pretty simple to understand, see at the bottom of the page
Page created in 0.*** seconds with ** queries.
the number of queries is the source of the problem, but the problem don't come from SMF, you see, some host will limit the number of query a user can make in a time interval.
So if there's an average of 10 query each time a page is loaded and about 200 visitor a day, that make 2000 request a day, if the max question is set to 50 000 for a month then 30x2000 = 60 000 queries a month.
Now I know that you have several user to access the DB but some time one user exceed the maximum and the DB block the future request from this user.
Solution would be to ask if they could remove or increase the maximum number of request for your user.
