hot acid liquid comes up in my throat!

Hello , I would like to know when seeing a doctor what tests should i ask for because i feel sick . Stomach is constantly upset with indigestion acid and burning every now and then if i dont take my nexium for a few days i will get the hot acid liquid that comes up in your throat .My question and concern is when i walk especially stairs or hills or even slightly elevated sidewalks . i have this burningin my chest and throat feels tight and dry and cold almost liek i been running in the cold .Is it heart,ashtma or my stomach .Inever had an ashtma attack but i took a test after a myomectomy done in 2004 beacuase i had a lung infection after surgery . i wanted to know more about thyroid disease too.This past year i had new symptoms such as hives welts and very crampy dull extreme leg and arm aches all at different times apart . my temp is alot 96-97 i feel cold alot and sometimes really tired or cant sleep . i have extreme leg jerks twitches and skin crawly itches at night too thanx