Welcome in H.C.M.
I have gone through your query regarding swelling on back of tongue and throat.
Your symptoms are favoring for allergic Rhinopharyngitis, you are advice for these investigations-
1- X-Ray paranasal sinuses
2- Culture & sensitivity of throat swab.
3- Blood- CBC, ESR
, Blood sugar.
By inferences of these investigations and there clinical co-relation will disclose the facts for diagnosis that may be accordingly manage.