Is it gastric ulcer

Three-year-old female spayed Shih Tzu was presented with acute onset of vomiting at 2AM on Sunday. The dog vomitted about 20 times before presentation. In the last few vomits, the owner observed some fresh blood also. There was no blood in the vomitus initially. Dog was comfortable on abdominal palpation. CRT was nomal and there were no other abnormal PE findingsX-Rays were done initially and they didn’t show any obstructive pattern. CPLI was not available at the time of presentaiton so I went with symptomatic treatment and administered cerenia and sent the dog home with the gastro food. The dog ate the food well in the morning. Vomitted a small amount of food but afterwards, no vomiting. At night on Sunday, the dog started having melena. The owner brought the dog again to the clinic today. I did the blood tests and they were normal. X-Rays were done again but I did not find anything abnormal. I did the abdominal US and found some hyperechogenicity in the stomach wall. Could this be an ulcer and cause of melena? BMBT was normal. The owner is not aware of any rodenticide ingestion. No dermal nodules were noticed