Stiffness on one rein. Help please!

[FinalFurlong]

So my loan horse is incredibly stiff on the right rein, he feels really heavy down the right side only on this rein and heavy in the hand, it really hurts my hand and wrist.

This is especially with bending and around corners (he bends really awkwardly, in fact he doesn't really bend at all), I ride him twice a week for half an hour, his owner rides him the rest of the time. Has anyone got any advice?

 

[Izzwizz]

First things that spring to mind are to get teeth checked and saddle. The I would be doing some work on the lunge or a pessoa device, maybe with the help of a good Instructor.

 

[Ginger Bear]

Not being comfortable on right rein can result to ulcers .

 

[Marydoll]

Get the usual checks done to make sure theres no ongoing tack or physical problem but he sounds quite crooked, get a good instructor in to help you learn to work him straight and get him into your left hand and off your right by working properly from behind.
They should be able to give you suppling exercises to help,but its probably something youll need to ride through most days until he becomes more supple and responsive To your aids. Id also have him seen by a good equine body worker or physio
Its possible his main rider is crooked so id ask her about being checked by a physio as well