1)
What is "Hamek Besaro v'Hu Omed"?
1.
Rashi: This is limbs falling off.
2)
What do we learn from "v'Hu Omed Al Raglav"?
1.
Radak: It will not be amidst illness. Rather, while he stands [healthy] on his legs, his flesh and limbs will melt.
3)
What do we learn from "b'Choreihem"?
1.
Radak: When the eyes will melt, there will be a Chor (hole) in their place. Yeshayah said about this affliction "v'Samti Vahem Os v'Shilachti Mehem Peleitim..." (66:19)