Hello Windows,
Essentially, it is difficult to say. There are so many factors you have mentioned which may be associated.
As we don't know how or why IVIG works, we have a difficult starting point. What we DO know is that high levels of exogenous IVIG seem to keep the leakage at bay. There is no reason why high levels of ENDOGENOUS IVIG may not also keep it at bay.
Alternative lines of examination could include the ff:
The infection you sustained at the start may still be lingering.
The liver damage may have caused some circulatory change.
Erythromycin may have sarted a process of enzyme induction
Etc etc etc.
There are too many possibilities at this stage, but any way of increasng your IgG levels MAY help.
John