Yes back pain is a side effect of Viread. You might also want to check your hormone levels.
If it were me I would stretch and maybe do some yoga
Nice one stef and stephen,d vit d3 is it to b taking as a single dose or splitted
take 5000 to 10.000iu of vit d3, back pain is inflammation, not due to viread
Back pain is a common but minor side effect of TDF. According to drugs.com (https://www.drugs.com/sfx/viread-side-effects.html):
"Some tenofovir side effects may not need any medical attention. As your body gets used to the medicine these side effects may disappear. Your health care professional may be able to help you prevent or reduce these side effects, but do check with them if any of the following side effects continue, or if you are concerned about them"
So wait, and if back pain persists, talk to your doctor.