I once thought that I was allergic to Spaghetti Sauce or Marinara Sauce since I kept getting hives everytime I ate it. Then as I thought about it some more I realized that I was pregnant during the times that I ate the sauce.
With some thought and a look at exactly what I was eating during that time, I finally found out recently that I am allergic to the prenatals that I was taking when I ate my pasta.

All I can think about is the month I just had without my pasta. I might be something else entirely other than the burger.
What did you drink with the burger? Did the burger have those seeds on the bun? Why not do a test to pin point exactly what it is? Try eating the hamburger only. Then the cheese. Then the bun. Then a combo. Sounds a little tiresome but it seems like the only way you will get to the bottom of this. This is what I did and I found out it wasn't even the tomato sauce but something else.
Think about it.
Jodi