Nicky Henderson has revealed that Jenkins - former ante-post favourite for the Supreme Novices' Hurdle - has picked up a problem following his defeat at Kempton.
A smart bumper performer, he made an impressive start to his hurdling career at Newbury and was long odds-on to remain unbeaten over obstacles over Christmas.
However, he looked in trouble a long way out and was beaten 19 lengths into fourth by Alan King's Elgin.
"It has come to light that he does have a problem which has come to light after his race," Henderson told his Stan James blog.
"It's mainly bruising really but there is also some fluid around the tendon sheath which we drained yesterday and it has helped. It's very frustrating though as he missed a couple of pieces of work and we need to get going with him again.
"We are struggling, and how much the bruising is to do with his Kempton defeat, I don't know, and it's a setback we could have done without but we're nearly there.
"We have to catch up somewhere as he has got to have another run if we are going to even look at Cheltenham and he has to jump better so we'll be doing plenty of work in that department too."
Jenkins is now as big as 25-1 for the Supreme at Cheltenham on March 14.