Thank you for the query.Cortisone
suppositories are not good idea. Please note that steroids
can cause intestine wall degeneration. It wont accelerate healing. Moreover it can make it worse.
Fissure can be healed without surgery if it is not a chronic fissure. Hemorrhoids can be decreased only without surgery but you can not get rid of them.
White streaks can be everything including mucus (most probable) and suppositories parts.
I suggest you to consult your surgeon before you will start any other treatment. Rectoscopy should be done and stool tests. You can wait with this visit a week or so.
Hope this will help.