I think it would be an excellent idea to take her to the vet -just for a complete check-over. And not just a cursory glance at eyes, teeth, etc. But get them to run her bloodwork. It might cost a little bit, but you will get quite a good picture of her general health.
Then once you know for sure she's fine, you will know which "road" to go down to tackle this problem.
It probably is behavioural. But most dogs will eat, when they get starving-hungry enough! Not eating could be a sign of a health issue.
Once you know she's OK. then try a really good wholesome 5-star dog food. YOU know it's good stuff, and exactly what she needs nutritionally. Don't pander to her, however tempting it might be to do that, or you could make her fussy.
If it's a dry dog food, you could also add a little boiled chicken or fish, with vegetables like green beans, carrots or squash, with a little juice, so it will be more nteresting.
Then give her the food, and ignore her while it's down. Let her come to terms with her dog-dish in her own way. Leave the dish down for 15 minutes, no more. Then take it completely away. (store it covered in the refrigerator)
At the time for her usual next meal, bring it out again. If it's too ice-cold, add a little hot water from the kettle, and stir it. Test first to make sure it's not too hot. It isn't meant to be hot, just so it isn't bitter-cold.
This methd usually works, because the dog realizes the food is only there for a short "window", then it disappears. They do usually start to eat when they get that message.
At first it can result in some wastage of food. Because you couldn't keep a prepared meal longer than 24 hours. But that's to be accepted. Try this, it might help?
but also take her to the vet!!!!! and see what they say to do cuz im not a vet
it is going to take time for her to trust you all you can really do is show her lots of love attention. show her you aren't there to hurt her. keep encouraging her to eat. whenever i bring home stray animals i normally try food they would find on the street first...but something really yummy. so i have tried like slices of deli roast beef turkey. plain with nothing on it. not a whole but it has always worked! i know people not to but i do anyway because i want them to eat so badly. worth a try. and if they do eat it then i guess mix it with the food you want them to eat.
let me know what happens