opengl – Sequential rotation of matrices

Given a 3D object, I want to rotate it from a given pivot on any axis. My problem is that I always have to express the rotation and translation to the initial state of the object, which is a center $$C (0,0,0)$$ and without rotation.

For example, I will take a cube with each edge. `1.0` Long, and turn it around the upper right corner. $$P (0.5,0.5, -0.5)$$, $$90$$ degrees in the $$x$$ axis. This means that since $$C (0,0,0)$$ my cube will now have center in $$C (0,0, -1)$$ then my translation matrix $$T$$ will be translated by $$(0,0, -1)$$

I do it by keeping the initial coordinates of the pivot, rotating a bit my quaternion and then finding the offset between the new center and the previous one, and then the translation.

After rotating, I find the offset as follows:
To have $$T & # 39;$$ a translation matrix translated by $$P$$Y $$R$$ The Rotation Matrix Calculate $$A = T & # 39; cdot R cdot T & # 39; ^ {- 1}$$ and my scroll will be in the last row of $$A$$. Add this offset to the original $$T$$ And I have my new center after the rotation. Now this works fine, however, if I want to do a second rotation, my object receives a new wrong center.

My rotation gif here:

When I start the second rotation, I try to find the new position of $$P$$ regarding $$(0,0,0)$$ center after the rotations that should now be $$(0.5,0.5,0.5)$$(I do it right) and then continue the rotation, but my center is deformed in the $$and$$ Axis that I suspect is an incorrect translation.
I would like to ask why this happens and how to solve it.