I had a venogram for suspected iih (low cerb tonsils, no im not overweight). my results were very low (0s/-1). they suspected a csf leak but cant find one. i also have severe scapula pain and muscle mass depletion. what could this be?

Very difficult to give you a well thought out answer with so little information. There are many vascular,neurological and autoimmune issues that may play into these symptoms. Without a complete history, including past history, imaging results, labs etc, there is no way for me to give you a good answer.

Not feasible to clinically correlate your somewhat vague history associated with negative studies, and pain and atrophy which may or may not relate. Would suggest these challenges be addressed by an experienced neurologist at a nearby medical school. A second opinion is indeed in order.