I've checked my score weekly for probably the past six or seven years. What I've learned is... nothing lol. I do have a credit monitoring service that tells me when a change occurs and it's always coincided with something I've initiated.
I volunteered once and they pulled a sexual offender report on me, I was surprised and didn't realize who would run something like that against me until I realized it was the company I volunteered with and had agreed to that check in the paperwork I signed.
I use CreditKarma, Chase FICO score, AmEx Fico Score and BarclayCard's FICO checks. Haven't ordered the actual report in years.
I recently noticed they changed their tiering and raised the "number" that would qualify someone for "Excellent" score. So it now takes a higher FICO score to be considered Excellent, but they did not raise the ceiling of the best possible score of 850 from my understanding.
That to me essentially makes it harder for someone to qualify, and also forces most to pay higher rates as less are qualifying for the "excellent score" tier.
I've never been late on a payment so I don't know what it would take to drop 100 points, but perhaps a late payment or delinquency?
Did your reported SS earnings drop signifigantly? I noticed the years my wife was off for maternity with lower SS earnings reported, but still maintaining same level of credit has reducer her score temporarily. Similarly I was laid off one year and my score dropped the next year once SS income was reported.
My score also dropped when I closed out both of our vehicle loans this year. It's my understanding that score is related to the amount of credit one can consume efficiently.
I play the CC game, with a few new CCs every couple years, and also closing CCs here and there. Each time I do that it drops my score a few points but slowly rebounds.
I've noticed if I push the balance higher than like 10% of the total credit cards available balance it drops the score. I do carry a balance on 0% cards. Since I have the money to pay it off, I am fine with that and prefer to use someone else's money for those short term high dollar purchases as long as its 0% interest.
One final thought... Does anyone else have joint credit with you? A mortgage, a car loan, an authorized user on a credit card? They could perhaps be impacting your credit if that's the case.