Welcome in H.C.M.
I have gone through your query regarding swollen gland below the jaw, Stiff tongue and pain on speaking and swallowing.
Your complaints clearly shows that you are having pathology at the base of tongue, it may be any infective lesion as blister
or ulcer. Sharp edges of last molars are also sometimes hurts the tongue and giving these type of symptoms.
Presence of node below the jaw should be considered carefully because it may be simply because of infection at posterior part of tongue and such infective nodes always responds to antibiotic. If after the course of antibiotic nodes persist than consultation with ENT doctor will be necessary for thorough examination of your pharynx and relevant investigations.