Cat issue: Hello and I need your help please!

[JennieV]

Hello everybody! I will be posting an introduction of myself shortly, but right now I really needed to ask you for your valued opinions.
My kitty, Max, a 5 yr old domestic shorthaired, indoors cat only, has been behaving kind of weird lately, I would say about a month, he is scratching excessively, loses hair in patches, his fur went very dull and looks awful, almost as if he was rolling under a car... just a couple of days ago he developed these red bumps, they are dry, but he is VERY ITCHY, I can tell, because he no longer licks himself, he bites...I took him to our vet yesterday, she said its some kind of food allergy, and put him on Medi-Cal. But what I need to know is : Has any of your cats experienced this before? What was the cause? Do you have any recommedations for me other than change of food? That would take time and I was hoping theres some kind of product for immediate relief, even if it is only external. :sad: I gave him a bath about 2-3 weeks ago, but that didnt seem to do much good...:sad:
I (and Max) appreciate any and all advice in advance!
Thanks!!