Bella won't eat

Bella is a 4 Y.O. female brindle. She has always had issues with her weight. We found out at age 6 months she had an allergy to chicken and has been chicken free for 3.5 years. 4 weeks ago Bella decided to give up eating. We tried all the tricks to include adding bone broth, hamburger rice, and wet food. These options worked for a meal or two but then back to nothing. Took her to the vet and ran blood test, checked teeth and stool. All tests were normal, stool was soft. Bella was given "entice" to spark her appetite, flora to put on her food for her tummy and an antibiotic for her soft stool. It's been 4 days and Bella has eaten about 1.5 cups of food total. Yesterday we bought CBD oil, first time with the hope she would get her appetite. Its been 2 doses, .05 of a dropper and she has slept and continues to be lethargic. I'm defeated as to what I can do at this point. I'm retired and with Bella all day. Has anyone experienced this with their boxer?