I think there is an update so you witnessed major drop in your DA and PA. There have been some updates and I would like to quote Kyle from the MOZ community forum, here is what he says -
"The Mozscape Index update yesterday includes even fewer urls, root domains, subdomains and total links than the previous Index from May 5th. You can compare the size of the Indexes on the Mozscape API Updates page.
Most likely, with the smaller Index these new links, and even previously indexed links, are not being picked up. Therefore, less links are being used to calculate your domain authority score.
I would say the drop in your Domain Authority is due to the size of the index. Try checking out your competitor’s sites to see if their domain authority dropped as well. I know mine went down slightly yesterday.
You don’t have anything to worry about, just keep earning quality links. I know it is tough to see your domain authority drop when you work hard to earn/build links, but the data used from one Index to the next has not been consistent, so don’t worry too much about the increase/drop in domain authority from one index release to the next.
If anything, track your domain authority over time and compare it to the size of the index to get a better idea of how your link building is performing. Unfortunately, that is the best answer I can give at this time."
I am quoting him here to let you know that you are not the only one who witnessed the drop in your DA or PA.