Suddenly allergic to watermelon

I’m 57 and have been lucky I can’t remember being allergic to any foods until yesterday. I ate a whole lot of delicious watermelon and right afterwards my stomach became very painfully bloated and my nose was completely congested. Benadryl worked but I wonder, can this just go away or what? I read somewhere that watermelon allergies can be triggered by pollen I. The air so maybe it could be seasonal/? NGL I want to try a little bit to see what happens.