Hello Anice!
I read through most of your post here on the forum, and I can relate to the Lumbar fusion and all of the questions you pose here. I too had a lumbar fusion (double) and I had a very rough time of it for several weeks. My surgeon also went in from the front, and I have nerve damage near the groin area.
I went back to work at the 8 week mark, and I would never recommend it to anyone having a double lumbar fusion. I even wore the hard chest/back brace for a couple more months while at work.
If no one has informed you, it can take 12 to 18 months for a fusion to fully heal, and it also takes several weeks for the nerves to come back alive before you will know the end result. Don't be surprised if your pain remains with you for the rest of your life, as it is very common. Today, I take a combination of several meds to maintain my pain.
I hope they can find what is causing the knot giving you fits. Yes they may have to do a little tissue repair, but the fusion itself should be stable and in tact.
One thing that is important and you should have been coached on by your surgeon, is walking. Walking is very important to the fusion process and helps promote it.
You may be tempted to do more laying around because of the pain, but again exercise or some sort of activity is important.
Good luck, and this forum is a great place for support. So visit often as you need.
SE