Poor Jimmy. He sounds like he has an internal illness unfortunately. Lots of diseases can cause constant vomiting and lethargy in A Pomeranian including: pancreatitis, a foreign body obstruction, kidney disease, liver disease and an infection just to name a few. 3 days of being ill is too long to try anything more at home or to wait to see if things get better. At this point I would highly recommend taking Jimmy to your local veterinarian for bloodwork +/- radiographs to diagnose the underlying problem so that we know what treatment he needs to hopefully make it through his serious illness. Here is a financial resource website if needed
http://m.humanesociety.org/animals/resources/tips/trouble_affording_veterinary_care.htmlAnd carecredit.com
I would take him to the vet asap. I hope that Jimmy is able to make a full and speedy recovery. Best wishes at the vet and take care of that fur baby.