Hi, I'm Currently In South America And After Completing A

Hi,
I'm currently in South America and after completing a hike up a volcano I have started experiencing really bad GERD, as well as headaches, muscles aches and an inability to eat accompanied by a loss of appetite? Furthermore, from this hike I got some rather large blisters which stupidly I have not kept clean. Is this another side affect of altitude sickness or something worse?
Regards
James