Hello and welcome to HCM ,
or postural fall in blood pressure is often related to other medical problems as you have stated like diabetes
, autoimmune disorders
,endocrinological disorder and it is even a side effect of antidepressant drugs.your physician can better relate these two.
Fall in the blood pressure cannot be related to placement of dental bone grafts or removal of wisdom tooth. though i suggest you get an OPG radiograph done which will show if there is any infection near the placement of graft or other vital structures.
i suggest you to consult a physician and evaluate the symptoms. take care.