Try dough for a day program. They will provide you the funds you need in order to close with your seller then of coarse turn around and sell to your end buyer. Let me know how it goes. If you want some info regarding that service shoot me an email. Good luck
Most lenders will not let you fund your first with your second. You have to have separate money. There are some title companies that do back to back closings and are aware of what is going on. Some private funding investors will provide your funding for cheap.