You can get useful FICO Score 8 credit scores using the CreditCheckTotal $1 trial -- just make sure to cancel the trial in a week or less. You get 3 FICO Score 8s from all 3 bureaus for $1. You can do it unlimited times if you want to.
Also, get a free FICO Score 8 from CreditScoreCard.com monthly -- it is truly free and gives you your Experian FICO Score 8.
One thing to know is that Credit Karma uses "Vantage Score 3" which is the same score that TransUnion was fined MILLIONS for in 2017 by the Feds for telling people it's a useful score. Vantage Score is a cheap "educational" score that a lot of predatory credit card blogs provide in hopes you'll listen to their poor advice and sign up for a card (they can make a lot of $$$ if you sign up through them).
As such, I feel that Vantage Score unfairly penalizes new accounts -- which is probably why your score dropped. New accounts can lower your chance of getting approved for new credit, so that penalty on Vantage Score probably makes sense but it isn't mathematically accurate.
Use Credit Karma to monitor your reports -- it can be pretty accurate and it shows a lot of useful information. But don't rely on their scores for anything but generic information.
Here's a chart of my Vantage Score versus my useful FICO Score 8 this year on TransUnion's bureau:
They don't trend well together much. Lots of opposite movements!