Hi gpm,
where is the tumor located? Leaning behavior I have seen in animals who seizure or look like they will anyways. I would probably take into account "confusion" etc, especially if a new symptom (neurological). What are the skin eruptions like? My cat with rodent ulcer coughs a lot, licks a lot has reoccurring lesions over his body and has also had inside the mouth. His symptoms pointed to ars as well, but it hasn't had much of an effect on his condition.