Dots? I must of missed those. Not ure what they would be. Are they fuzzy or do they look like grains of salt?
Stress coat can be used as a water conditioner and/or to help with fins/scale regrowth. I use it as a conditioner since it can be found at walmart as well as pet stores. The directions say to use 2X the dosage if being used as a medicinal aid. So if you have a 5 gallon and you want to treat torn fins you would fill the cap up which is for 10 gallons.
I have Prime and that is also a popular option for water conditioner. I know it can neturlize ammonia, nitrite and nitrate but not sure what else it may do. I dont care for Prime because it stinks horrible of..I don't know but it smells bad. LOL
Honestly - clean, warm water is really all you need. I just happen to have a bunch of stuff on hand because I drove from alaska to New York with my bettas, so I bough Amquel plus and Krodon fish protector which are supposed to be good to use for shipping.
I'm wondering - how much decor did he have in the original tank and how much did he have in the hospital tank? Sometimes they dont like empty spaces. If you get one of those big, leafy, oversized silk plants - that might help.
My HM started bitting after I did a water change and fell asleep before I released him from the cup he was acclimating in

After that, he was a bitter till the day he died. I think his fins might of been too heavy or something.