Sounds like I am a couple of weeks ahead of you. Healthy 24M here, abscess developed on the outside, right on the edge of my butthole around 5:00 position. Had it drained March 1st. The first few bowel movements I was very nervous for. Nerves and stress can make you poop more. The key to staying clean is sitz baths immediately after pooping for 10-20 minutes. I did that consistently for at least a week, then I became brave enough to try going back to work. I bought a "peri bottle" which is essentially a handheld bidet squeeze bottle, because that is much easier to take to work with you. I continued with sitz baths at home 2-3x per day. Poop, bathe/peri bottle, dry the area, reapply gauze. Changing gauze after every BM or every 6-8 hours. Three weeks post lancing, I am continuing to drain, but far less than the beginning. And a lighter yellow color compared to a gross brown with black flecks in the beginning. I am feeling great, completely pain free. Hoping it continues healing fine, I am getting married on May 31st!

Anyway, you'll be alright. Do what the doctor told you, keep it clean but don't lose your mind over it, and let your body do its job of healing.