Sir,
By the way you describe your problem
You are having diplopia for distance
Are you suffering from
diabetes?
We need to do refraction and give proper glasses prior to tests
We need to do few tests for coming to any diagnosis
As you say your problem it could be due to abnormal retinal correspondence with fourth nerve involvement or severe dry eye
We need to ask few more questions and need to do few more tests
It would be nice to initiate an online consultation with any ophthalmologist to discuss more or visit near by ophthalmologist
If problem is very severe you can patch one eye which has more power or less vision
Please be careful while walking downstairs