If your FICO score is under 680, I wouldn’t count on it. You’re not going to get good rates, or even a loan, without 20-40% equity. I always recommend renting for most people; owning a home is (in general) a bad investment, regardless of what realtors have bamboozled us into thinking.

Second mortgages are pretty much a thing of the past.
In a buyers market you really don’t want to sell unless you have no other choice. I would say rent out your home until the market rebounds and then look at selling. As far getting a new loan its not that hard. You will need at least 3.5% for a down payment and a 580+ mid score.

It is harder to find a 2nd mortgage through a reputable company, one that is not going to have hidden fees and agendas. Investigate any thing promised to you carefully and remember that if it sounds too good to be true it probably is.

Just ask. I just refinanced to knock more than 2% off my interest rate & got approval over the phone from my mortgage company.