Well, without the cash to cover both mortgages out of pocket you are pretty limited in your choices. Even if the value was good, it probably wouldn't be realistic to sell it and close in 60 days so you would likely be out of pocket there too.
What are you looking for from finance guys to "get you out of this situation"? Short sale, loan or line of credit to cover you until you get a new renter, buy parent's house and get cash back at closing to cover the expenses of the other???
In order to give you any kind of real advice details would be needed as to exactly what your goals are and what the finances are like with you/your house/your parent's house.