I have had Ankylosing spondylitis which is inflammatory arthritis, which was diagnosed in 1961 when I was 21 years old.
I have taken anti-inflammatory medicine ever since. The medication is pretty good and I have been lucky.
I started running (around 3 miles) about 3 or 4 times a weeks when I was 33 (I am 70 now). I did the first two London Marathons( 1981 and 82).
The first thing you need to do is get a diagnosis of exactly what type of arthritis your mother has. Arthritis a word which covers is a wide range.
Then do some research on the internet. It should be possible to buy a generic medication, probably much cheaper than a brand name, but chemically the same.
I know some people swear by herbal / alternative etc medicine (some even think the world is flat) but for my part, I have no faith that they work in general. So my advice is don't waste your money on them. I am fairly sure you should be able to buy the generic medication in Phil, cheaper that in the West and then adding transportation costs.
I suggest first you