Had a hemorrhoidectomy three days ago for three internal Grade 3 hemorrhoids and have been doing very well. Had my first small BM this morning with no issues. Felt pretty great as far as I'm doing...
Until a few hours later I went to use a Tuck's wipe to see if I had any stuck poop in my crack. When I went to wipe I felt a large hard lump on the outside of my anus 
I don't understand because I only had internal hemorrhoids removed... Is this normal?
Why aren't you calling your doctor? Everyone's normal is different. Your doctor has seen your butt, and knows your butt, and is your butt expert.
It's Saturday
No doctor but if your in pain you could of had a small prolapse, could go back after a few days with plenty of rest or maybe or wait to see your doctor. I prolapsed after my surgery but was in excruciating agony. Still not 100% after weeks but pain has died down. Plenty of rest and hot baths. Feel for you and hope you get sorted soon 🙏
Firstly, I agreed with checking in with your surgeon as soon as you can. Monday perhaps? GP will be the second option. But the surgeon will be able to give you a more accurate assessment.
Secondly, from my own experience and many other people’s posts, it takes weeks for the swelling in the area to come down. Even it was removal of the internal hemorrhoids, the entire area will be somewhat swelling after the surgery. What looks like another hemorrhoid is probably the swelling. It took me 3 weeks for it to come down half the size, and I’m at 4 weeks post op and still have small lumps.
In the early days, they’re bigger, harder and tender; painful when pressure applied. Slowly, they will shrink and become softer and smaller.
There may also what is called “bridge” where the incision is made - like scar tissue, which will take a long long time to reduce in size.
So don’t panic! The recovery is painful but sounds like you have some good local anesthetic from the surgery, numbing the area. Take sitz bath frequently - it soothe pain and help reduce in swelling. Use ice pack in between sitz bath on 10 min , off 10 mins. to reduce swelling.
Hope it helps!! Good luck!!