My grandfather is 92 years old. Since 1 week he has a lot of pain in his arms and almost doesn't like to eat something. Either I like to help him to get rid a little bit of the pain in his arms, because I think he has problems with the blood circulation.

1. The issue with the pain in the arms could be a sign of a heart condition. Choosing the sets like you did above is therefore a good choice. Maybe you can support this with herb: https://coastchiropractichove.wordpress.com/2012/01/28/craetegus-oxyacantha-the-heart-tonic-hawthorn-berry/

2. Cistus incanus, (Zistrose Tee) is a good treatment to push the immune system. 
Then what is always good to push the blood circulation is a footbath with herbs and natural rock salt. Also using "Franzbrandwein" to rub the Arms and the back. It can help him to feel more strengh. When you use your hollow hand to smoothly clapping the Franzbrandwein in to the skin on the back. Good for the lungs.

3. Pain has many varieties.
Deep Nerve pain, Surface pain like shingles, Muscle pain, bone pain, sharp, dull, electric...
Having a better idea on what kind of pain he's having could be useful to decide what if anything can be tried.
Where the pain is specifically too.
The upper arm, lower, entire arm, elbow, wrists, surface, deep?
and is it Constant, or intermittent and fading or increasing throughout the day?
Like needles and pins or like run over by a truck?
Does Cold help or is Heat packs better?
Gentle massage help or make it worse?
Any history of surgery that the pain could be Blood Clots?
Remember we can't diagnose here.
Perhaps a Visiting Nurse practitioner could visit to make an assessment without needing to go into the hospital?

For more details, please check the link:
https://www.spooky2.com/forums/viewtopic.php?f=12&t=8536