The neck dissection is contributing to the problem - the lymph fluid has lost part of its pathway therefore is stagnant and not really moving - kinda like a sewer backing up. Movement - a good long walk daily, and lymphatic massage learned through a professional will help build new pathways and allow the fluid to drain - this in turn will help with the tongue swelling. Also at this point her mouth is likely very sensitive. Some foods - acidic (sugary products, vinegars etc... ) and spicy foods will also cause swelling. hugs!!!