For Denkall being "the best vet gear in Mexico" according to alot of guys, that particular product is quite crappy imo, for lack of a better term. The pain is common bro. I used it without adding Equipoise ONCE, then learned my lesson. I felt like I injected it with a whalehook, and could barely lift my arm for like 10 days, and it got no better with time. The test-flu is also pretty bad initially, but I get the same deal with most all of the Mexican Vet Tests. That one, along with the Denkall Aqua-Test give it to me the worst it seems.
For Benzyl Alcohol Pain: Mix EQUIPOISE at a 2:1 ratio of EQ:T400(or whatever item is causing said pain).
For Test-Flu: Hot tea, Aspirin, time, get into some cardio. That part of it isn't really that unbearable. Rather just uncomfortable. The BA pain though(as you said), is NO joke. It's bad.