For certain she tld them it was more than 'a 1 out of 10' if the crew called Medlink. Majority of the cc are female, they know what's usual and what's not.
She might have taked it up hoping for an upgrade, then freaked out when the crew followed procedure (ask questions) and followed up (call Medlink if in any doubt of fitness to fly)
I flew with some muppets but no senior is dumb enough to offload for 'period pain'. The result would have hinged entirely on the questions asked and the answers the pax gave. As for being embarrassed, she was obviously ok with talking about it to her boyfriend loud enough for a passing crewmember to hear.
Then again, this is the Sun doing the reporting...