The former Royal Marines reservist and Invictus Games gold medallist, 33, revealed that the injuries he suffered while serving in Helmand in Afghanistan have been causing him some trouble on the dancing show.
In May 2011, JJ was caught in an IED blast which caused him to lose two fingers, as well as suffering facial and leg injuries due to shrapnel and his right elbow was badly damaged.
He revealed on The One Show that the shrapnel which still remains in his body can still cause problems, especially while competing on Strictly.
JJ explained: ‘A couple of weeks before the competition actually started I first got an infection in my leg.
‘As you say, I’ve got bits of [shrapnel] from Afghanistan all over my body and sometimes they just sit there dormant and happy but particularly when you go through periods of exhaustion, which everybody in the process is finding at this point, your immune system dips a bit and that’s when it decides it’s not happy to be there.
‘So it’s infected one of the scars in my leg but I put up with it at the beginning of the competition and it’s been… there’s Viennese Waltz this week which is a lot of close body contact.’
He added: ‘As alarming as it sounds, it’s not unusual – this is just what you have to live with. It’s the side-effect of being alive.’
JJ and his dance partner Amy Dowden have made it through to this weekend’s show after narrowly missing out on the dance-off, which saw Caroline Quentin be eliminated after facing off with Maisie Smith.
The One Show airs weekdays from 7pm on BBC One.