@bigdaddysaints -
If your father is experiencing chronic pain- especially lower back, see if his dispensary sells CBG or CBC - optimally as a 3:1 or 4:1 CBG to THC ratio.
I like tincture in the morning - a heavy Sativa 1:1 CBG and use a distillate pen throughout the day. I am able to focus and work all day without back pain from an falling accident.
If the issues is more muscular or joint and has trouble sleeping, same ratio as above but CBN is the most active sleep cannabinoid. My wife will use a black tea CBN before bed - No THC and buys it at the grocery store.