What Causes Body Rashes, GERD With Indigestion, Chest, Arm And Shoulder Pain?

i have red blochy rash over body comes and goes feels like a sunburn when ever i get into water sometimes, also have indegestion (gerd) a lot lately and like little sharp pains in chest arm shoulders and hands ,fingers i know i have arthritis in hands bad also my shoulder has croniic rotator i forgot what they called . any way could all these be part of the same or diffrent rash i kinda had before but never this bad and seems to get worse with sweating which i have always done a lot of all my life. b