Your little guy is certainly looking better than in the first picture you posted. The E-collar he's wearing, or "donut" is far more preferable to the plastic ones, since this is soft and looks more comfortable. It seems he may have to continue wearing this for a while, so you might want to look into a "Bite Not" collar, another alternative to an E-collar. Cats can eat, drink, play and see around corners because their peripheral vision is unimpeded. It's available at www.carealotpets.com
for $19.95 plus shipping.
It's a possibility that your cat has a food allergy. You might want to try a new brand and flavor of canned food. Make sure it's high quality - no by-products, preservatives or artificial colors. Also avoid wheat and corn.
Hissy had a good suggestion about Transfer Factor. For information about that see the thread in this forum "What is Transfer Factor?" www.thecatsite.com/forums/showthread.php?t=49143
Salmon oil is also very beneficial for skin problems. Most cats can take the contents of a 500mg cap mixed into food once per day.
Hope Kitty continues to heal and feels better soon. Please let us know.