Can my 7 year old take adult tums (calcium carbonate)? He is complaining of burning in the back of his throat. The problem is out of nowhere. Not long term

May be strep? If your son likes honey, give him one or two teaspoons to chew and swallow slowly - his scratchy throat may go away in a day. However if his throat is bright red with swollen tonsils, a strep throat screen will help to identify a very contagious condition that will keep him out of school. In the mean time, make sure he doesn't drink after any one else or others drink out of the same glass as he.
Yes. He can take Tums (calcium carbonate) but his throat pain may not respond to it. He may have an infection in the throat causing the burning. If he is complaining or "heartburn" and the Tums (calcium carbonate) helps you may have an acid reflux problem but I suspect a pharyngitis and recommend he be tested for strep.
Yes, but..... Tums are calcium carbonate. One or two should be OK--like drinking a glass of milk. However, if your son is complaining of a sore throat, he may have a viral or bacterial infection (pharyngitis). I'd be concerned about strep. Recommend he be checked out for it.