Need advice from nurses or doctors?!!?

So my boyfriend started to feel sick on Wednesday night. Just nauseous and threw up once. Thursday got even worse. Throwing up and a really sharp pain in the middle of his stomach. Had chest pain and trouble breathing as well as a low grade fever. He went to urgent care and they told him to go get tested for Covid so he did. Later that night at around 9pm he went to the ER because he was on the floor crying because the pain was so bad. He said it was the worst pain he had ever felt. When he went to the ER he got plenty of tests ran on him. (Rapid covid test, chest x-ray, got tested for appendicitis, something with his pancreas as well as his gallbladder) I’m not sure EXACTLY what they did but they checked for a ton. All came back negative but they said he has high liver enzymes. He has alot of gastrointestinal problems as is so you could tell he wasn’t overreacting. Since all the tests came back negative they said it was probably a stomach virus and sent him home with some pain meds. It’s now Saturday and he’s still having this pain in his stomach. The nausea has pretty much gone away and he hasn’t thrown up since Thursday but this pain is still there. He says the pain meds haven’t been helping and ibuprofen makes the pain worse. He’s also been using a heating pad but that hasn’t been doing much either. He told me it’s hard to walk and stand. He’s going to the ER again right now but I don’t know what they’re gonna tell him since they ran tests and already said it was a virus. Is there any way the doctors could have been wrong? I’m starting to get really worried and want to know what actually could be happening. He was completely fine on Wednesday until around 8pm.

UPDATE:

After a few hours in the ER they said that it’s Mesenteric Adenitis. He should be feeling completely better in about a week! So glad it isn’t anything too serious. They prescribed him pain medication to help as well.