Yes, would also suggest trying a longer fast.
During 14 days the cleanse rather doesn't have a chance to reach and remove arthretic deposits in one's joints (unless, of course, one is a very slim and non-toxic person).
From my own experience: if you decide to take 24-30 day fast for healing reasons, it is very sensible to use vitamin / mineral supplements, plus extra doses of vit C and silica. One can skip them on shorter fasts, but it seems wiser to protect yourself against deficiences on longer ones.
Other medication should be discussed with someone supervising your fast. But, very probably, again on no food your body will stop inflamatory processes, co you may not need anything.