It's a theory.
After eating a bunch of fried prawns, I became so itchy that I had to take anti allergy meds. Two days later, I fried a few potatoes (with a brand new cooking oil, opting not to reuse the one I used to fry the prawns) and just after 4 hours, my right hipjoint is aching like ****. As that has happened several times already (I usually take a painkiller for relief), I theorized that those potatoes might be the source of my pain after all. So instead of taking a pain killer, I experimented with Diphenhydramine to see if the pain would go away. It did.