13 year old Jack Russell Terrier

Question
I just typed all of this, but don't think it was sent properly, so I'll try again.  My 13 year old Jack Russell quit eating his dry food 3 or 4 weeks ago.  He lost a lot of weight before I realized what was happening.  His spine sticks up and he just looks bad.  I first tried Moist and Meaty packets, which he ate about 2 days---now he'll eat on a can of dry for a few days, than reject that too.  If I give him  more than 2 serving spoons at a time, he'll probably throw up.  He also has trouble having a BM, stays hunched over straining a long time, but does have some small results, but he's not eating much either.  He does urinate, it is dark, but not bloody red.  He doesn't drink enough either, only very little.  Especially after having a BM, he frequently can hardly walk---particularly going up a step.  I'm wondering if I can try an egg or something, raw or cooked?  I want him to eat, but not vomit of course.  My husband of 28 years died a few weeks ago at the age of 53.  I just can't bear the thought of loosing something else I love.  Any ideas of how to feed him?  Thanks so much.  JK

Answer
More tempting food is seldom the answer.  He could well have a problem the vet could easily find and correct.  A small dog like that should have some good years yet.  Bigger dogs don't live as Long.  We just had to put a 15 year old Lab to sleep.  It is tough.