multiple web queries failing but single queries work

Hey guys, 

I'm having an issue in pulling multiple tables through a Rest API call in Power BI. 

I'm able to create a data model from each call using a get data -> Web and using the url string given to me from the documentaion. 

There are 7 seperate tables that need to be pulled in. The REST API generates a csv file which Power BI captures. 

The REST API is using my logon credentials and I believe that I can't access at the same time from multiple threads. 

I'm getting the following error when I hit a Refresh on Desktop

DataSource.Error: Web.Contents failed to get contents from 

URL I'm accessing

Internal Server Error

Every single one of the queries executes fine when its the only query refreshed. 

Does anyone have an idea how I can stagger these (Either by triggers or by delays) so that there won't be concurrent calls using my credentials.

Thanks in advance