I am sorry about the migraines that have started up... Is that your only
symptoms post closing the pfo?
An American nickel has about 30% nickel in it. Take a shower and then
clean a nickel really well ( with alcohol wipes and soap and water too)
than take a sterile bandage and tape it to your freshly showered and dried
Keep it there for 24 hours, remove it and see if there is any signs of
allergy or inflammation in general ( redness, itching, swelling).
I am actually doing the test now pre procedure lol.