How many inquiries are you talking? Under 5? the answer would be no. Massive amounts, a possibility. From the apps, how many were approved, as this would decrease your AAoA substantially if you were approved for quite a few. Also are all your cards carrying a balance except one? Or is a card(s) carrying a higher balance this month vs last month? If so you may have crossed a higher utilization threshold and could have added to the higher decrease in score.
Where are you obtaining your score(s)?
Yeah, over 10 can dinged you pretty bad. I definitely would garden and pay down on debts, your utilization may or may not be high for it to have sunk to 590. But the inquires will not be scoreable in one years on FICO 8, I would let them age off then since there are pretty many on there. Keep utilization low. So when your scores raise, you will be able to obtain decent cards, not sub prime, with high APR, or Annual Fees. Keep the payments timely, and your scores will rise. Just work on ridding any baddies that you can, either if paid off, using goodwill letters pleading for removal, and any open offering any pay for deletes. With credit, it is definitely not a sprint, but you will reap the rewards before the marathon is over.
Did I hear right, that none of your 10+ INQ were approvals?
Regarding the inquiries, the OP says he probably took around 10. Are you talking 10 total across all 3B, or are you talking 10 specifically on EX? If it's 10 across all 3B, we can venture to guess that maybe 3-4 of them landed on EX. Also what's important to know is how many inquiries you had on EX prior and how many you had post-spree, as that can help determine how many points you may have lost from the inquiries.
Yesterday, my EX was 635...this morning I checked, and it had dropped 45 points to 590. What in the world?? I reviewed the report and didn't see any new negatives. I know I have probably made more inquiries than necessary lately, and I plan to garden for a while, but would that really result in a 45 point drop? I'm not going to get discouraged, because I know I've been taking the right steps, etc., but a drop of this magnitude has taken me aback. Any ideas?
To know what caused the score drop you'd need to review your EX report from before the score drop and your report after the score drop.