3 years post op and throwing up after eating the last few week, what is wrong with me?

Inside the pouch issues must be ruled out such as ulcers, stricture, kinking of the sleeve, bile reflux, etc, all these can be diagnosed endoscopically and/or upper GI contrast studies (fluoroscopy, CAT scan). It’s must be addressed ASAP 

Your symptoms are concerning, especially given your history of gastric sleeve surgery and hiatal hernia repair. There are several possible reasons why you might be experiencing nausea and vomiting after eating. One possibility is a stricture, which is a narrowing of the stomach or esophagus due to scar tissue. This can make it difficult for food to pass through, causing it to sit in the stomach and trigger nausea and vomiting. Another potential cause is gastroparesis, a condition that slows down stomach emptying and could explain why you are vomiting undigested food hours after eating.
A recurrence or complication of your hiatal hernia repair could also be contributing to these issues. If the hernia has returned or the repair has failed, it might be causing severe acid reflux, nausea, and difficulty keeping food down. Gastric sleeve stenosis, where the stomach has narrowed over time, could be another explanation, leading to a blockage and food intolerance. GERD (gastroesophageal reflux disease) may also be playing a role, as severe acid reflux can sometimes cause nausea and vomiting.
Ulcers or irritation in the stomach lining could be another factor. If an ulcer has formed in the stomach or along the surgical staple line, it may cause pain, nausea, and difficulty tolerating food. In rare cases, an intestinal obstruction or twisting (volvulus) could be responsible, leading to symptoms of nausea, vomiting, and discomfort.
Since you are vomiting multiple times a day and struggling to digest food properly, you should seek medical attention as soon as possible. This could lead to dehydration and malnutrition if left untreated. Your doctor may recommend an upper endoscopy (EGD), a barium swallow test, or imaging studies to determine the underlying cause. If you are also experiencing weight loss, abdominal pain, or difficulty swallowing, it is even more urgent to get checked out.

Hello, thank you for sharing,
The best recommendation is to contact the doctor who perform the procedure, it's for your best if the doctor checks on you  and/or prescribe medication.
In addition to other criteria such as medical indications and safety, behavioral health assessments, and so forth I recommend that you go to your certified doctor so he can guide you and do the check up necessary to assist you.
My  Best Wishes