Chronic pain and dizziness when looking at iphone for more than 2 - 3 minutes

Hi, I have iphone 4S. For few months I have noticed that my body has become quite sensitive to it's use. The way it affects me is that I have chronic pain in my left arm which usually stays calm as I am having meds for it. But with the use of iphone,when doing texts or looking at the camera pictures for more than 2 - 3 minutes, my same pain starts to creep up and finally dizziness. Initially when it happened I change the display to high contrast, i.e. white on black background. That helped for a few days but now it doesn't. The same reaction happens with iPhone 6. Also, with computer use I get the same reaction. But on the computer after I changed the background to black and lessened the brightness of all colors, now I am able to work on the computer without pain going up, except if I am browsing Internet and a big blob of white color appears.

It really is strange, I have got my eyes checked, no issues. I know for sure it is something on the display of iphones and computer monitors that give me this strange reaction. As a result I have limited the use of iPhone for only making calls.

Has anyone come across this strange problem? thanks, rsinha