The area appears to be healing well. The redness most likely is where the sutures were. That will get better. You have to keep in mind that you had a body part removed. It's not going to be comfortable. Allow 2-4 weeks for complete healing. That being said, if at any point the pain gets worse,...
Your concerns would be infection or dry socket. A dry socket after bone grafting is very rare. I doubt that's what's happening. It is possible some of the bacteria was still in the socket and is causing an infection. Or it could be normal post operative pain. You just had a body part removed. If...
The membrane keeps skin cells from growing down into the area. It is important that the membrane be kept under the gums, and the stitches will aid in this. If the membrane becomes exposed to the saliva, you might lose the whole graft. You should consult with your surgeon.