If you sell now it would be a short sale - unless you are going to pay the difference between what you owe and what you sell for. If you do a short sale, you have to prove financial hardship to your lender(s). If you have a provable financial hardship, you will not qualify for a new loan for a new house. Now, if you can pay the difference, there will be no effect to your credit because it would not be a short sale.
If you cannot pay the difference, another option might be to rent out your current home.