Virtually every lender is experiencing turmoil, some more than than others. If your loan is an FHA loan, the underwriter may have suddenly extended their review times due to the volume of loans they are currently facing. If your loan is being financed by an investor group, they may have suddenly changed their rules and requirements. Even large banks such as Bank of America or Wells Fargo are undergoing tremendous changes right now. Many lenders have drastically cut their workforces and are now overwhelmed.
Lenders are also taking extra steps that had gone by the wayside in past years such as last-minute verification of employment, bank accounts, funds to close, etc. It is frustrating for all involved but there is little to be done. The lender will release docs and send funds when they are good and ready.
In the meantime, avoid spending money for anything other than bills, food and gas until your loan is closed. It goes without saying--now is no time to buy a new car, RV or quit your job. If you need new appliances for your new home, don't buy them until AFTER you've been given your keys.