Help

Now that I’ve confirmed this is the right group for help on my plant.

Can you guys help me treat it? So I’ve owned it for about 4 months, she was doing good… Until she started getting gnats nonstop and cinnamon and spraying a hydroxide peroxide solution stopped working so I decided to repot it since it still had the old owner’s soil and this pot doesn’t have a drain… I did fix my watering and even got a moisture meter to only water when it’s super dry, but that wasn’t enough because I’m pretty sure it already developed fungus by then.

Well, for some dumb reason I sprayed its roots when I was repotting her since I noticed a bunch of baby gnats were all over the soil and the pot. I deep cleaned the pot and like I said, sprayed the roots (it still had oil soil hard on the roots) and then put it in the pot and waited days until I watered it, around that same week I gave it fox arm big bloom fertilizer and since her neighbor got gnats again I also mixed bonide with the first 2in of soil (so gnats are 100% gone from my house) but now I’ve noticed she’s gotten these brown spots which she had tiny ones before all of this stress but after I repotted her she’s gotten way more and I know for sure it’s not from overwatering cause I’ve barely watered her since repotting her about 2 weeks ago and I’ve sprayed her with neem oil and it seemed it made it worse. I’m scared she’s going to die. Can anyone give me some guidance please??
No direct sunlight.