Database Error

Hi, sorry to disturb you, but since 2 days now, i got this message :

“”Error establishing a database connection
This either means that the username and password information in your wp-config.php file is incorrect or we can’t contact the database server at pf7-mysql.online.net. This could mean your host’s database server is down.

Are you sure you have the correct username and password?
Are you sure that you have typed the correct hostname?
Are you sure that the database server is running?
If you’re unsure what these terms mean you should probably contact your host. If you still need help you can always visit the WordPress Support Forums.””

if i try to click on “edit page” on too many page, for let you know what i mean, i got a website where i use tags, so i got a page per tag, when i create a new content, i gon into the page, hold CTRL and click on all the tags for open their page quickly.
I recently change my hosting to a lower one in therm of capacity cause i dont need it, and since that (2 days ago) when i open all that page of tag, i click on edit go to next, click on edit, go to next, etc before i have no problem and all page running and go to edit mode, but now, it dont support more than 3-4 page running before let me click on another one, otherwhise i got that f*****g message appear immediatly on the page, before even try to run, so my question is : how can i fix that and dont have it anymore for let me work like before, cause i dont have time to wait that a page is in edit mode before click on another one, and most of all, he make me the same about click on “save modifications”, i click on it, go to next page, click on it, etc and i have the exact same message.

Tell me if i had to have my past hosting program back for having the oportunity for work faster like i describe it to you.

Someone told me that maybe its the login of database who are not the same as the one in the wp-confing.php, but i check and they are the same, so i wait for you answer and im gonna try everyday for see if its not maybe the fact that i go for a lower capacity hosting program, and the time it move on hosting society for everything is back like before.

Thanks in advance, have a great day 🙂