googley, keep going back to the doctor and telling them that you aren't better.
I had to do that a few years ago when they wanted to discount my diarrhea as 'functional' (meaning they had no idea why). When I went back they looked at it more closely and found out why. So I think they sometimes say it's nothing as a first response, then see if we come back if it doesn't resolve itself.

When I was having chronic pancreatitis (I didn't know then what it was) the first doctor I saw, when I was very dehydrated and could barely stand, said it was the flu (because the patient before me had the flu, he said). He reluctantly offered to send me to the GI doc, and I chose to do that and it was the right thing to do. I was sick.

So, keep going back. I hope you feel much better soon!