I Have Been Got To The Doctors For Quite A

I have been got to the doctors for quite a few months with same problem they keep saying I have to much acid in my stomach but I really don't think that's the problem I keep feeling sick all the time sometimes I feel like my chest is really hevi and feel as if I can't breathe sometimes and am getting a lot of pain down the left side just under my kidneys you have eny idea what the problem is?