Sorry for your situation. You might want to consider selling the home in central valley for a loss. I would speak with your tax accoutant to find out whether you will get relief from loss on the home when you do a short sale. The reason i think this might help your situation is with the money you are paying every month to cover both mortgages is not giving you any room to save for down payment on a home in San Diego.
I would make sure you handle everything with you tax accountant and current lender on your home in central california, if you can get that home sold, and start focusing on San Diego that might help with saving and stress level in your home.
I working in the San Diego Area as a realtor, if you have any other questions please don't hesitate to ask.