don't worry,its very much normal..scaling is to remove calculus and stains existing on teeth.so that adequate hygiene can be maintained before putting braces(orthodontic treatment ).
as you know you had problem with gums earlier too that is gingivitis
. its good that you have got scaling done.
now it will definitely take some time for your gingiva
to come back to normal. once it is normal , you will have very little or no bleeding at all. slowly bleeding will also stop.a healthy gum has no bleeding , no redness
and no swelling .
you can use any toothpaste but just see it has, sodium mono flouro phosphate in its ingredients .
my advice to you is do frequent warm saline rinses and do use a mouth wash like hexidine 2% also periodically.
you have to really really take care of your gums now so that they can help you in your orthodontic tooth movement. for that you just have to maintain hygiene and above measures. your gums will be problem free.