Please ensure your tea and coffee intake do not exceed 3 cups per day. More than this will deplete your absorption of magnesium, needed for the relaxation of tense muscles.
I'd suspect you have bruised yourself in the pelvic tissue area from the fall and that is responsible for the back and side pains.
Atrosan (Devils Claw) has no interactions with other medicines and might very much help your overall joint symptoms but for more immediate help, our Atrogel (Arnica), applied 3 times daily should ease the immediate pain. It is best applied before bed and upon waking to make sleep more comfortable and ease morning stiffness.
Much as you might feel disinclined to move, please try to as movement reduces stiffness and aids circulation which results in faster recovery.
My blog - Dealing with pain - Part 3 - may be of help.