I'm at a crossroad and need advice.

My wife and I have a plan to 'house hack' a 4 plex so we put our SFH on the market to sell. The plan is to owner occupy a 4 plex with an FHA loan so that we only have to put 3.5% down. Almost immediately we got a good offer on our home which was surprising for my market (our house has excellent views so that helps). The buyer put $3k in earnest money without us even asking. She got the inspection report back with no major concerns and we agreed to her offer. All is well (or so we thought) so we found a great off market 4 plex and made an offer to buy it and our offer was accepted. The same day our offer was accepted, the buyer for our house backed out for unknown reasons. We explained the unfortunate situation to the 4 plex owner and they were kind enough to keep us under contract and have extended the closing date for 60 days thinking that would give us enough time to sell our home. I doubt they will let us keep kicking that can down the road for much longer. Once they put it on the market it will definitely sell fast - it's priced right and will cash flow with just 2 units rented. The market has slowed to a crawl here and now we're worried that we'll miss out on this excellent deal.
We can't afford a 20% down payment and we already have an FHA loan on our existing home we're trying to sell. We can't have 2 FHA loans at the same time so we need to sell our home first.

So here's my question/s:

What would you do in this situation? Is it possible to get a hard money loan for the 4 plex and refinance it later (after our home sells) using an FHA loan? Are there any other strategies I've not though of? (I don't know anyone with enough funds to do private money).

Thanks in advance.  

@Shane Wood Are you marketing your house aggressively? Advertise everywhere you can to get that buyer. Try to sweetened the deal by offering some money toward closing cost, home warranty, staging, etc. The sooner you can get rid of it the better.

Yes we are marketing really well although I'm sure there are a few more things we can try.  It's staged very well too.  We even dropped the price recently to see if we can pull in some of the previous people who viewed our home.   It's viewed more and saved more on zillow and realtor dot com than comparable homes for sale in my area.   Thanks for your advice. 

@Shane Wood  I hope everything works out for you.