If you have jock itch, you almost certainly have a yeast infection under your foreskin. Yes, by all means use one of the jock itch creams. They should be safe to use inside your foreskin, but sometimes fillers are used, so you'll have to try it to see. Those designated for vaginal use are definitely safe. Do not use the antibiotics you have mentioned. Symptoms often vary, so itching is not necessarily one of them.
Do not use any kind of body wash under your foreskin. Soap removes beneficial bacteria which are there to prevent infections. Smegma is not dirty, so removing it is not necessary for proper hygiene. You are better off doing nothing at all than trying to keep it squeeky clean, and I am not kidding about that. The act of sexual intercourse utilizes smegma as a lubricant and makes it disappear. A simple rinse tidies thing up.
If you are having bouts with jock itch, athlete's foot and this foreskin infection, you should get a health evaluation to rule out diabetes. If there is no diabetes, take a good look at your diet. Start eating more vegetables and drinking more water instead of sodas.
Are you really a Cali guy? Where?