health problem for 11 yr old beagle

my 11 yr old female beagle has recently recovered from a bladder infection. last night she started ahving a hard time urinating. I have also noticed tht her urine looks almost like a mucus. This afternoon she has also started to vomit a very yellow liquid. Could the infection have come back or could she possibly have something else?

The first two symptoms (trouble urinating, mucus passing) are consistent with a bladder infection.
   
Vomiting, however, is not consistent with a bladder infection so I am suspicious that something else is going on.
   
If this were my dog, we'd be going back to the vet.
   
Good luck, hope this works out.