ok if you can peel it off it is an insect called a scale. they will eat your plant and multiply. you can kill them with neem oil and other such products. you can usually find these type of things at walmart for around 6-10 dollars. if you are budding dont use any foliar insecticide that isnt organic and fast to break down as you dont want to smoke any pesticide haha!! you can also make a tobacco type tea spray for your buds and leaves theat wont leave a residue on your plants after a week maybe shorter. just soak a bunch of old cigarette butts in some water overnight and use the water nicotine mixture to spray on you plants. this will get rid of most types of bugs.
make sure you scales though. could also be stem rot if the spots seem to be rotting and start to get larger and your stem seems to be getting weak in that spot. stem rot is fairly easily distiguished and goes right along with root rot so if you have one you may have the other. im not sure how to stop it once it has started. i believe it is due to overwatering, make sure you let that soil dry so that your pot is light when you pick it up.
if they are scales you will be able to pull them off and look atthe underside of them, they are actual insects.
try looking in the bugs subforum there is probly pictures of scales posted somewhere in there.
found a couple, sorry they are so large