It can be tricky to assign links between what you take and any reactions you get. Some are obvious, some not so much. Find a course that makes sense and stick with it long enough to develop a sense of what your body needs.
Salt and water, yes. 1/2 tsp salt is great, with 2-3 liters of water.
Vitamin C, B vitamins, and some minerals, yes. Especially magnesium and selenium.
Consider stopping the nascent Iodine to trial Ginagirl's suggestion. Far better to avoid unnecessary testing if stopping the nascent cures your throat pain.
Iodine as Lugol's with Vitamin C or as SSKI are time-proven.