We Have A 10 Year Old Lab Mix Male Dog.

We have a 10 year old lab mix male dog. A few weeks ago he stopped eating his evening meal (we feed him Kibbles and Bits dry food most of the time). Then after a few days, he stopped eating or drinking for a few days. For the past week he is interested in eating and drinking water again...and gobbles up the chicken we give him, but within an hour throws it up again. He is very think now and not much energy, but still goes outside and sniff around some. We are not financially able to spend hundreds of dollars for testing, etc. It is so sad, and a hard decision, given his age, too. Any advice?