First and most important, ignore Credit Karma scores if that is your source. Lenders don't use Vantage scores, so you shouldn't either. You need to know and follow your FICO scores. The easiest way to get one in a matter of minutes for free that you can refresh monthly to see your progress is by heading to creditscorecard.com.
As for paying down $1500 in debt, that's a great thing and you should be proud of that. It's 100% impossible that paying down debt would ever cause a 90+ FICO score drop. In fact, in 99% of cases it's impossible for a debt paydown to cause any score drop. I don't believe your situation falls into that 1% where it could happen (paying off all revolvers to $0 and having them all report $0, paying off your only installment loan) so no need to even consider that. A revolving debt would result in either a score gain or no score gain, not a loss.
In order to determine that, you'll have to list out all of your credit card balances along with their limits, both before and after your recent paydown. Based on those numbers we can go ahead and offer you up some solid advice. Just list them out like Card 1: $300 balance on $1200 limit, Card 2: $1500 balance on a $5000 limit, etc. then reference the one(s) you paid down, like paid down the $1500 balance on Card 2 to $800, for example.
