Right side of my tongue is swollen and it's difficult to swallow. what to do?

See MD immediately: You should seek medical attention immediately. Swelling in the tongue has the potential to cause an airway issue and can lead to a life threatening situation. Given your previous history with allergic reactions, it is possible that you are experiencing allergic type symptoms and a medical evaluation is highly recommended.

See doc ASAP: Because different structures populate the "tongue" area in the back of the mouth: muscle, tonsils, salivary glands and ducts, nerves, blood vessels, and the potential for numerous residual tissues that can cause cysts or tumors. In addition to trauma (e.g. Hot coffee burn), a stroke, for example, can cause altered sensation and/or swallowing effort by damaging nerves in the brain/spinal column.