I know months can feel like decades in that early stage. I vividly remember it myself... But it is essential to give yourself the best possible chance to recover... Try and remove as much stress from your life as possible. If you need to take time off, do it... If you need to lock yourself in your room, do it... Whatever helps with stress... You can quickly get your life back on track once you recover or learn to deal with this.
I would also add that self blame/self loathing is great fuel for stress and anxiety. If at all possible, forgive yourself for taking risks with drugs and realise that no amount of wishing you hadn't done something will ever make it so... It's wasted energy and added stress, so just forgive yourself for doing something that millions of others do, learn and move on. (easy said than done, i know!).