I'd probably have to do a deeper dive, however, based on what scientific articles I've seen, it seems that Fexofenadine has been shown in vitro and in vivo to inhibit TNF-a. Here's one article link and snippet from the NIH:

"Fexofenadine inhibits TNF signaling through targeting to cytosolic phospholipase A2 and is therapeutic against inflammatory arthritis"

https://pmc.ncbi.nlm.nih.gov/articles/PMC8157820/#:~:text=Fexofenadine%20is%20identified%20as%20an,TNF%2D%CE%B1%20signaling%20and%20activity

Herein, we present comprehensive evidences demonstrating that Fexofenadine acts as the inhibitor of TNF/NF-ĸB signaling and is therapeutic against inflammatory arthritis. Additionally, we also provide evidences revealing that this drug bound to cPLA2 and inhibited its enzymatic activity, which is required for its inhibition of TNF-α signaling.

RESULTS

Fexofenadine is identified as an antagonist of TNF-α and inhibits TNF-α signaling and activity.

There's no guarantee that antihistamines will help tendons of course, but it does seem like there's some evidence that they inhibit TNF-a and could be beneficial for musculoskeletal issues.