Osteopath / Physio / Chiropractor...which?

I have a 21 yr old Connemara X Arab. Gorgeous little mare who looks 10 not 21 - she is in great health and has tons of energy. Showing some stiffness for past 6 months which looked to be coming from the stifle area. Vet couldn't find root cause - not a chronic problem as no muscle wastage, no arthritis. It used to improve on warming up but never gone completely. She is just a pleasure horse for a bit of hacking and my children adore looking after her as she is so gently. She is not used for any hard work at all and won't be. I put her on Stride HA for a month to see if any improvement and it was minimal.

Anyway got saddler out today in case the saddle was causing a problem as she is progressively getting more uncomfortable and bucking the past few weeks. She thinks her back and one shoulder may be sore. She gave me a chiropractor's number but I can't decide if I should get an equine physio or an equine chiropractor or osteopath.

Re physio one very reputable lives next door but is in my opinion a bad handler of horses sort of launching at them instead of gently approaching and handling sensitively - this mare who is the gentlest horse reared and took off in a panic on the lunge the one time I had this physio over as just jumped up on a stool and attacked her back, in general was rough when examining.

Any ideas or opinions on which type of practitioner to go with?