could i go zero down for VA with a 620 credit score?>
Your 620 credit score alone would not prevent you from qualifying for a VA loan. You may view some general VA loan info here: http://vegaslender.net/mortgage-info/va-home-loans/

I live in mesquite Nevada and currently have a VA mortgage at 375 with quicken loans I owe about 131,000 on a single family home
It sounds like your DTI is going to be your main stumbling block with 2 mortgages. You may want to seek some advice about your credit card debt before adding it to your home mortgage. You can take a look at general guidelines of different loan programs here: http://vegaslender.net/mortgage-info/.