Thrips or else ?

You had insects indeed, like trips and you have been burning your plant a bit with threating your plant against them. Make sure your lights are off next time when doing this. I personaly don't like housegarden solutions but just buying good decent sprays. When having insect problems, you should also spray afterwards to make sure all of them will be death or don't come back, even the eggs. Get something like Canna Cure, i really like to use that, it even has nutrients in it for your leafs. Goodluck growing :)

Thanks for your helpful tips mauigrown ! I use a "ready to use" black soap solution I bought in a shop, with a 5% dilution. Plus I sprayed at night as recommanded... So if it's still thrips, I'll spray black soap this night again ! Hope I'll get rid of these bad guys.