Hi.. Thanks for the query.. As per your complain a feeling of heaviness in tongue like you have eaten areca nut and also having astringent feeling with a history of taking thyroid medication and also Sintamin that is an anti depressant is pointing towards side effect of medication.. There can also be an indirect effect of these medications as they can cause dry mouth and lead to thinning of mucosa inside mouth causing irritation, inflammation, soreness and discomfort leading to Stomatitis and Glossitis [inflammation of tongue].. I would therefore suggest you to consult your treating Physician and get evaluated and explain your immediate symptoms in details.. An examination of the oral cavity and tongue has to be done.. In case if the side effects of medicine is the cause then dose reduction or switching to other drugs can help.. As of now you can chew sugarfree chewing gums to stimulate saliva flow.. Dink plenty of cool water.. Avoid spicy foods.. To control anxiety you can do deep breathing exercises and meditation.. Hope this helps.. Regards.