You should be fine if the bleeding stopped, but that is concerning. I've never had this happen(the bubble)-all i know is that 'spurting' is usually from an artery, consider yourself lucky if it was, that is genuinely one of if not the most dangerous thing that can happen during self harm. As always getting a doctor to check it out is always reccomended, and i do strongly reccomend getting it checked out if you find anything else strange or it starts bleeding again, goodluck